Oligosaccharides，a kind of plant stimulatinghormone，had the effects of improving crop stress resistance and promoting cropgrowth.To elucidate the effects of complex oligosaccharides application on increasing yield and efficiency of cucumberplants，the effects of complex oligosaccharides on plant photosynthesischaracteristics，yield andthe microbial communities in the leaves，roots，and soil around the roots of cucumber at three growth stages were analyzed after complex oligosaccharides preparations applied in the early and growth stages ofcucumber.Using a greenhouseplot experiment，three treatment groups were setup:clear watercontrol，chemical conventional treatment and complex oligosaccharidetreatment.Cucumberleaves，roots，and soil samples were collected during theflowering，fruiting and seedlingstages，respectively.Cucumberyield，chlorophyll content and antioxidant enzyme activity were measured at eachsamplingperiod，and high -throughput sequencing was performed to detect the bacterial community structure and composition of thesamples.Compared with clear watercontrol，the application of complex oligosaccharides increased theyield of cucumber per plant by4.96%.The content of chlorophyll in cucumber leaves wassignificantlyincreased，and the relative value of chlorophyllcontent(SPAD)in the complex digosaccharide treatment was significantly increased by 6.14%-11.46% compared toothertreatments.At the sametime，the activity of superoxide dismutase in the leaves was increasedby39.9%-81.5%，the activity of catalase wasincreased by8.4%-40.4%，and the activity of peroxidase was increased by 1.19%-18.5%.The high -throughput sequencing analysis results showed that the application of complex oligosaccharides increased the abundance of Sphingomonassp.and Methylobacteriumsp.in the leaf microbialcommunity，both of which have the effects of promoting plant growth and assisting plant diseaseresistance.Inaddition，complex oligosaccharides increased the abundance of biocontrol bacteria Bacillussp.in the microbial community of the rhizospheresoil.The application of complex oligosaccharides in the early and growth stages of cucumber could increase cucumber yield and plant antioxidant enzymeactivity，delay plantaging，and increase the abundance of beneficial bacteria in the plant growthsystem. It could provide basic data for further revealing the mechanism of action of complex oligosaccharides.