Abstract: An experiment was conducted by taking different mulching materials and varied mulching quantity in order to study mulching effect on soil nutrient contents and soil enzyme activities in the soil under Prunus salicina plantation in the Karst region. The mulching materials included Trifolium pretense, Astragalus siniucus-Lysimachia christinae (1∶3), Medicago sativa-Lysimachia christinae (1∶3), and Conyza blinii, with no mulching as the control. Three levels of mulching quantity were set as 2.5 kg/m2, 50 kg/m2 and 75 kg/m2 in the experiment. Compared to the control, the results showed that the mulching with Trifolium pretense, Astragalus siniucus-Lysimachia christinae (1∶3), Medicago sativa-Lysimachia christinae (1∶3) significantly increased the contents of total soil N, total soil P, the alkalihydrolyzable N, the available P and the soil enzyme activities. The urease and phosphatase enzyme activities in the soil were highly correlated with the N and P nutrient contents in the soil. The effect of mulching materials on the soil nutrient content was ordered as Trifolium pretense > Astragalus siniucus-Lysimachia christinae (1∶3) >Medicago sativa-Lysimachia christinae （1∶3）> Conyza blinii > CK. The effect of mulching amount by Trifolium pretense was ordered as 75 kg/m2 > 50 kg/m2 > 2.5 kg/m2 > CK. The contents of soil N and P nutrients varied similarly between the 40 and 120 days after having been mulched with the Trifolium pretense, which increased at the early stage and then decreased along with the time.