Setting up post poured belt is one of the most important measures for temperature control and crack prevention of mass concrete, but current specifications have not given unified and clear rules on the spacing of post poured belt. In this paper, an inverted-T shape concrete structure on soft foundation in Yangtze River Delta region is taken as the research object. The temperature and stress field of concrete during construction under different conditions are simulated by finite element method, and bottom plate’s and gate pier’s recommended spacing of post-casting belt is obtained when poured in different seasons. This will be of providing a certain reference for the construction of such mass concrete structure.