In recent years,with the rapid development of shipping economy,waterway regulation projects are frequent in the Yangtze River basin.Although waterway regulation projects can improve flow conditions,they also have a certain impact on fish habitat.To explore the impact of different waterway regulation projects on fish habitat,we take Luoqi Reach of the upper reaches of the Yangtze River as an example,and use numerical simulation method to compare and analyze the changes of habitat suitability of Four Major Chinese Carps before and after the waterway regulation project from the perspective of ecology and hydraulics.The results show that after the waterway regulation project,the very suitable area ratio of fish habitat increases by 1.21% at most,and the unsuitable area ratio decreases by 1.85% at most.Moreover,with the increase of water level and flow,the sub channel upstream of Luoqi will produce a suitable habitat environment for survival.