【Objective】 Although some studies have been reported on environmental risk assessment of single-factor contamination of triclosan (TCS), a typical pharmaceuticals and personal care products (PPCPs), little has on effects of combined contamination of TCS and cadmium on ecosystems. The aim of this study is to evaluate comprehensively environmental risks of combined contamination of TCS and cadmium in soil ecosystems.【Method】A laboratory incubation experiment was performed and a combined toxic effect prediction model was used to evaluate ecological toxicity of single-factor and/or combined pollution of triclosan and cadmium on soil microbial and enzyme activities involved in soil carbon and nitrogen cycling. The incubation experiment was designed to have four treatments for triclosan contamination, i.e. 0, 1.0, 10.0 and 50.0 mg kg^-1 dry soil, two treatments for Cd contamination, i.e. 0 and 10.0 mg kg^-1 dry soil, added in the form of CdCl₂, three combined contamination treatments, i.e. 1.0/10.0, 10.0/10.0 and 50.0/10.0 mg kg^-1 dry soil in triclosan/cadmium, and three controls containing neither cadmium nor triclosan. Each treatment had three replicates. The treated samples were incubated at 25℃ in dark. The soil respiration, protease and sucrose activities were measured on the 7th, 14th, 28th and 56th day of incubation. 【Result】Results show that both the single-factor and combined pollutions of triclosan and cadmium had soil respiration activated, inhibited and then activated again. In the soils under single-factor stress of either Cd or TCS, soil respiration was significantly activated on Day 7 with activation rate being 18.52 %, 25.26%, 27.98% and 18.45% for Cd 10.0 mg kg^-1, triclosan 1.0, 10.0 and 50.0 mg kg^-1, respectively, and began to be inhibited after 14 days of incubation, and activated again at the end of the incubation (Day 56), with activation rate being 24.16%, 41.84%, 31.56% and 21.41% for Cd 10.0 mg kg^-1, triclosan 1.0, 10.0 and 50.0 mg kg^-1, respectively, which were significantly different from that in the controls (p<0.05) . Furthermore, the degree of activation seemed to be related with the concentration of triclosan (p<0.05) spiked. In the soils under combined stress of Cd and TCS, regardless of ratio, soil respiration was stimulated on Day 7, with the effect declining with rising TCS concentration; inhibited on Day 14 and Day 28, with the effect declining too, with rising triclosan concentration, and stimulated significantly again at the end of the experiment (Day 56). The contamination of Cd and TCS, either single-factor or combined, stimulated protease activity with the effect declining first and then rising during the process of incubation and peaking on Day 56, with activation rate being 94.5%, 31.8%, 42.1% and 68.2% for Cd 10.0 mg kg^-1, triclosan 1.0, 10.0 and 50.0 mg kg^-1, respectively, in soils under single-factor stress of cadmium or triclosan, and being 98.0%, 110.3% and 102.7% for TCS/Cd 1.0/10.0, 10.0/10.0, and 50.0/10.0 mg kg^-1, respectively, in soils under combined stress. However, the degree of stimulation of protease activity was not significantly positively related to the concentrations of triclosan (p>0.05) in the soil. The contamination of Cd and TCS, either single-factor or combined, inhibited invertase activity during the whole incubation period. The effect peaked up to 81% on Day 14 in soils under single-factor contamination of cadmium, and was negatively related to concentration of TCS in soils under single-factor stress of triclosan, and did not show any dose-effect relationship in soils under combined pollution of Cd and TCS. The joint effects evaluation model shows that compared to single-factor pollution of either triclosan or Cd, the two pollutants in the treatments under combined stress acted jointly on soil respiration, but not always the same way. Their relationship varied with the time, from antagonistic to synergetic and then additive. Their effects on soil protease varied from synergistic to additive and then to synergetic, while their effects on soil invertase activity were mainly synergistic. 【Conclusion】Throughout the entire experiment, the contamination of Cd and TCS, either single-factor or combined, firstly stimulated then inhibited and in the end stimulated again soil respiration, stimulated protease activity, and inhibited the invertase activity. The joint toxic effects of triclosan and cadmium varied with concentration and duration of the exposure. Therefore, it is suggested that in future studies, joint toxic effects of chemical pollutants in biosolids and soil should be taken into account in health risk assessment.