The upstream behavior of fish after crossing the dam is critical for fish to find suitable functional habitats for spawning, baiting, etc. At present, most researches in China focus on quantifying the swimming behavior of fish upstream through the fishway, while the analysis of upstream behavior after crossing dams has rarely been reported. In this study, passive integrated transponder (PIT) telemetry was used at the Songxin Dam in the Heishui River, a tributary of the lower Jinsha River, to monitor the upstream behavior of Schizothorax wangchiachii, the target fish of Songxin Power Station, after crossing the dam. In view of the influence of changes in hydrological conditions on post-damming upstream behavior during monitoring, a Cox proportional regression model coupled with multiple factors (flow, water temperature, river rise and fall rate, diurnal rhythm relative fatness, etc.) was established by using survival analysis method. Meanwhile, the optimal model parameters were selected by utilizing the AIC model guideline to identify the key factors affecting the efficiency of fish's post-damming upstream movement. The results indicated that(1)The upstream effect of Schizothorax wangchiachii in the Songxin fishway passage rate is significantly better than that in the river channel; (2)Water temperature and rise and fall rate of river discharge are the key factors affecting the passage efficiency of Schizothorax wangchiachii after crossing the dam; (3)Water temperature was negatively correlated with the success rate of river upstream after Schizothorax wangchiachii crossed the dam, and when the water temperature exceeded the optimum temperature for Schizothorax wangchiachii, the success rate of river upstream was decreasing with temperature; The upstream success rate of Schizothorax wangchiachii after crossing the dam was positively correlated with the rate of river rise and fall rate, where the river successful upstream rate of Schizothorax wangchiachii in the situation of rising water is higher than that in falling water, and the river upstream success rate was increasing with water rise rate; (4)Although there was no significant effect of diurnal rhythm on the success of river upstream after crossing the dam for Schizothorax wangchiachii, the results showed that 61% of Schizothorax wangchiachii chose to upstream at night. This research provides scientific basis and reference for restoring fish habitat and optimizing ecological planning of small hydropower plants.