Abstract: Aiming at the problems of poor seedling growth quality caused by environmental temperature and accumulated soil temperature in traditional cold region maize planting. The objective of this paper is to optimize the temperature and humidity parameters of maize seedling raising, and to use the closed seedling raising technology for reference. Through uniform test and stepwise regression method, it was determined that the phenotypic traits of maize seedlings were significantly affected. The Design-Expert 8.0.6 software was used to carry out response surface analysis, and the regression equation and response surface graph were obtained, and then the temperature and humidity parameters of maize seedling were optimized. The experimental results showed that, in the closed seedling-raising system environment, the light environment was set unchanged, and the concentration of CO₂ was constant at 440×10^-6. Under this condition, the optimized maize seedling-raising was suitable for growth. The optimum parameters ranged from 25℃～26℃ and humidity48%RH～52%RH. Temperature and humidity had significant effects on the phenotypic traits of maize seedlings（plant height, stem base width, chlorophyll content SPAD and leaf area coefficient）（P ＜ 0.05）. The phenotypic traits of maize seedlings based on closed seedling system met the agronomic and transplanting requirements（BBCH-scale 13-15）, and compared with the live broadcast of Daejeon, the results showed that although the difference in phenotypic traits of maize seedlings was not obvious, the breeding time was shortened by about 10 days. The experimental results can provide reference for setting temperature and humidity during seedling raising in cold region, and lay a foundation for mechanized transplanting of cold region maize.