Based on pot-experiments with ¹⁴C-hydroquinone and ¹⁵N-urea, the distribution, forms and transfer of hydroquinone (HQ) in a soil-rice system were discussed. Residues of hydroquinone in soil increased with the soil depth, with an average of 0.041mg/kg. 13% of hydroquinone was decomposed as CO₂ and H₂O due to biochemical and physiochemical actions. 49% of the residue-¹⁴C entered into high moleeular compounds and could not be extracted by solvents, while 45% into low molecular compound. Metabolism, distribution and absorption of hydroquinone in rice were determined. The contents of hydroquinone in brown rice and stem (and leaf) were 0.07mg/kg and 0.05mg/kg respectively. Results of pot-experiment show that exogenous hydroquinone participated in metabolism of C in rice and promoted the utilization of urea-N in soil. Limiting value of hydroquinone residual in soil after long-term application of slow-release urea was calculated to be 0.044 mg/kg, which was far lower than the hydroquinone standard 0.20mg/kg soil for human health in U.S.A. It could be concluded that long-term application of slowreleasing urea is very safe.