【Objective】Complex in composition, loose I structure and low in cohesion, engineering taluses are places where hazards, like soil erosion, mud-rock flow and landslip, are likely to occur under the action of rainfall runoff. 【Method】 Based on field investigations of the engineering taluses formed during town construction processes in Chongqing, engineering taluses of purple soil and yellow sandy earth, commonly seen in the region, were selected as the objects of the study. On the taluses, field water scouring experiments were carried out to explore dynamic processes and mechanisms of water infiltrating, flow generating and sediment yielding on the underlying land surface under taluses different in rock content, relative to hydraulic condition, in an attempt to illustrate morphology and evolution process of the erosion and distribution characteristics of sediment particles in the erosion on the talus slopes. The field scouring experiments, designed to have three flow rates (i.e. 5, 10, 15 L min-1) and three slope gradients (i.e. 30°, 35° and 40°), were conducted during the peiord from August to November, 2012 at the Stationary Soil Erosion Experiment Site for Production and Construction Projects in the Southwest University, Chongqing. 【Result】Results show: (1) water infiltration rate in the soils of the taluses declined rapidly first and then gradually leveled off with scouring going on and magnitude of the fluctuation varied with scouring flow rate; water infiltration rate on the underlying surface varied in the range of 0.4 ~ 1.7 mm min^-1, and the mean infiltration rate was in a power function relationship with the scouring flow rate, and so was the erosion modulus on the underlying surface of the taluses of different nature. It is, therefore, feasible to estimate erosion moduluses of taluses formed during the processes of various urban construction projects by scouring flow rate; (2) runoff yield rate on the talus slopes rose first and then fluctuated, exhibiting a wave-like curve with the scouring going on, which indicates that scouring flow rate is the major factor affecting runoff rate on the slope. With rising flow rate runoff rate increased significantly. When the scouring flow rates were the same, the mean runoff rate on talus slopes of yellow sandy earth was 1.89 times that on talus slopes of purple soil; (3) sediment concentration in runoff on talus slopes on different underlying surfaces rose first and then leveled off with the scouring going on and varied in the range of 0.21 ~ 1278.49 g L^-1 relative to scouring flow rate; during the scouring process, soil erosion transformed from surface erosion to gully erosion, affecting significantly or multiplying sediment concentration in runoff by 13.73 times to the most extent; the erosion process on the talus slopes consisted of three stages, i.e. sudden changing stage, active stage and stabilization stage, corresponding to the three stages of erosion transformation from surface erosion to gully erosion, i.e. surface erosion, rill erosion and waning of rill erosion; contingency and randomness of the occurrence of rills were the two major contributors to the fluctuation of sediment yield;(4) particle size distribution of the erosion sediment from engineering talus slopes varied sharply with scouring flow rate and with composition of the talus slope; the particles of the erosion sediment from the talus of purple soil were larger in size than those from the talus of yellow sandy earth. The erosion sediment from the talus of purple soil varied in the range of 2 ~ 10 mm in particle size, and that from the talus of yellow sandy earth in the range of 0.1 ~ 0.5 mm; roughing of the talus slope as a result of erosion makes it harder to restore ecology of the waste dumping sites. 【Conclusion】All the findings of the study may serve as important scientific basis for prediction of soil and water loss and restoration of vegetation and ecology on engineering taluses in Chongqing.