Abstract: After the autumn cucumber crop was pulled, three treatments of in situ straw returning（T1）, in situ returning with additional nitrogen fertilizer（T2） and no straw returning control（CK） were set up, and tomatoes were planted in the second spring crop to study its effects on tomato growth and soil environment, with the aim of clarifying the feasibility of in situ straw returning for greenhouse vegetables in alpine regions. The results showed that in situ returning of cucumber straw to the field and in situ returning of cucumber straw to the field with additional nitrogen fertilizer significantly promoted tomato growth and improved tomato quality and yield, and the yield of in situ returning of cucumber straw to the field and in situ returning of cucumber straw to the field with additional nitrogen fertilizer treatments increased by 20.7% and 34.4%; respectively, compared with the control, in situ return and in situ returning with additional nitrogen fertilizer treatments significantly increased soil pH and significantly decreased electrical conductivity, while significantly increasing nutrient content, increasing soil organic carbon and total nitrogen content, and improving soil enzyme activity, but in situ returning treatments inhibited tomato growth and decreased soil nitrate and the total nitrogen content and soil urease activity in the early stage. In conclusion, it was feasible to return straw to the field for greenhouse cucumber, in which the best effect of in situ returning of straw to the field was to increase nitrogen fertilization.