The influence of environmental temperature and humidity change cannot be ignored in massive concrete structures. Much attention is paid to the analysis on temperature field, thermal stress field, humidity stress field, and especially its total stress field. In view of this, an ideal spherical mass concrete structure is selected, and the temperature field, temperature stress field and humidity stress field are numerically simulated successively through ANSYS on the premise of considering only the impact of environmental temperature and humidity. Furthermore, thermal stress field and the humidity stress field are overlaid to obtain the total stress field. Results of the simulation are analyzed and conclusion is put forward. Through the numerical simulation of stress field, the crack degradation of poured massive concrete can be predicted so as to formulate temperature control measures.