Abstract: The dynamic effects of straw mulching on straw decomposition rate and soil enzyme activities in pear orchard play a positive role in promoting straw returning to field and sustainable agricultural development. In this study, nylon net bag method was used to investigate the decomposition characteristics of straw in pear garden, and soil samples were collected at different periods and different soil depths under 4 kinds of straw mulch. The activities of urease, sucrase, neutral protease and dehydrogenase were determined. The results showed that, in the same interval time, the decomposition amount of straw in the early stage was larger and the decomposition rate was faster, while the decomposition amount of straw in the later stage was reduced and the decomposition rate was slowed down gradually. The percentage of straw decomposition in the pear orchard reached 64.8% at 180 d, and the decomposition rate reached 1.62 g∙(g·a)⁻¹ at 90 d. Different straw mulching amounts had different effects on soil enzyme activity. Compared with CK, the activities of soil urease and sucrase in 10 ~ 40 cm, and neutral protease in 0 ~ 20 cm and dehydrogenase in 0 ~ 60 cm in summer and autumn were increased under three straw mulching amounts of 7.5×10³, 15.0×10³ and 22.5×10³ kg∙hm⁻²_, while the maximum activity of four kinds of soil enzymes appeared in 0 ~ 20 cm soil under 15.0×10³ kg∙hm⁻². The activity of urease and sucrase was 373 and 20.3 U∙g⁻¹ in 10 ~ 20 cm soil in summer, respectively, neutral protease of 0.76 U∙g⁻¹ in 0 ~ 10 cm soil in autumn, and dehydrogenase of 39.3 U∙g⁻¹ in 0 ~ 10 cm soil in summer. Pearson correlation analysis found that there were different degrees of correlation among different indicators, and the percentage of straw decomposition was significantly positively correlated with neutral protease activity but negatively with sucrose enzyme activity. The straw mulch of 15.0×10³ kg∙hm⁻² has the best effect on soil enzyme activity in pear orchard.