In this paper, a two-dimensional non-steady-state heat transfer model has been established for the working conditions of thick slab in a steel plant in China, a modification has been made on the basis of the nailing experimental results, the slab solidification difference of practice and prediction by field heat tracing model has been analyzed. The results show that the actual solidification end point of slab is more close to meniscus than prediction, the distance difference is 0.592m, the better soft reduction zone is from 0.2 to 0.9, which the level of central segregation can be reduced from the class B 1.0 to C 1.0.