Most of the small hydropower stations aim at maximizing the benefit of power generation.The ecological flow in the lower reaches of the hydropower stations is zero or nearly zero,which has an increasingly prominent impact on the ecological environment.In order to study the influence of ecological flow on power loss and the effect of its influencing factors,this paper selects Suichuan county,Jiangxi province as the study area,and Principal Component Analysis（PCA）is used to analyze the influence of ecological flow on power loss rate of small hydropower station.The correlation analysis shows：1）the influence threshold of river ecological flow on the power loss rate of small hydropower stations is generally controlled at[10%,20%];2）the first principal component of the power station efficiency attribute includes the annual utilization hours（M4）,the ratio of design flow to multi-year average flow （M5）and the water utilization ratio（M6）.The design head（M2）and design flow（M3）are the second principal components of power station output.The installed scale（M1）is the single main index of the third principal component.Among them,M2 and M4 have negative effects on the power loss rate,indicating that the larger the parameters,the larger the corresponding power loss rate M1,M3,M5 and M6 have positive effects on the power loss rate.The larger the parameters,the smaller the corresponding power loss.In order to ensure the rectification and evaluation for small hydropower can be carried out sucessfully,it is advisable to first examine the authenticity and reliability of M1,M4,M5 and M6,and then collect the nameplate data of the power station.Obviously,this study provides certain technical support and reference for small hydropower station evaluation and power loss compensation.