Catalpa bungei is a famous and precious high-quality timber tree species,and the government plans to promote it in the suitable regions of China,thus it is necessary to study on its water and fertilizer management.By using response surface methodology based on rotatable central composite design,stem height (SH),ground diameter (GD),biomass yield (BY) and leaf area (LA) of C.bungei seedlings were observed to study the coupling effects of soil water (W),nitrogen application (N) and phosphorus application (P)on growth characteristics of C.bungei seedlings through pot experiment.Results showed that both W and N had obvious positive effects on SH,GD,BY and LA of C.bungei seedlings,with a size sequence of N>W,whereas P factor only had positive effects on BY.Moreover,there were significantly positive interactions of W×N on growth characteristics of seedlings,while the interaction of W×P only had a positive effect on the SH.The optimized combination was determined by establishing a multiple target decision model synthesizing SH,GD,BY and LA,C.bungei seedlings achieved maximum growth when their actual irrigation,nitrogen application and phosphorus application values reached W=74.605%,N=4.710 g·plant-1 and P=2.009 g·plant-1 respectively.Also,the results of fitting model showed that there was a close correlation between fine roots (diameter≤2 mm) biomass yield and SH,GD.These recommendations can gain double functions of water saving and production increases and provide basic theory for seedling culture and afforestation of C.bungei for reference.