The effects of soil mulching approaches on water use efficiency, fruit quality and leaf nitrate reductases activity of capsicum (Capsicum anmuum L.), and as well as plant and soil nitrate allocation were studied in a green house environment. There were four treatments in the study, namely, control(CK), straw mulching(T₁), plastic film mulching(T₂), and straw and plastic film combined mulching (T₃). The results show that soil water contents are increased in the capsicum growth period for the three mulching practices, and plastic film mulching and straw and plastic film combined mulching can get high capsicum yields, water use efficiency of yield and economic water use efficiency compare to the other two treatments. Soil nitrate-N contents of the tillage layer (0-20 cm) are significantly decreased under the mulching treatments, the high the soil depths, the lower the soil nitrate contents. However, soil ammonium-N contents are not significantly affected by the mulching practices. Vitamin C content and pH value of capsicum fruit are increased under the plastic film mulching, while electricity conductivity, cation exchange capacity and nitrate content of the soil are decreased. Nitrate reductases activity of leaves are increased under the mulching practices, while total N content of leaves is decreased, and the N absorption amount per 100 kg yields is reduced significantly. In agriculture production, helped with scientific water management, plastic film mulching, and straw and plastic film combined mulching are feasible mulching practices to enhance capsicum fruit quality, environment security, fertilizer use efficiency and economic benefit.