Nowadays concrete-filled steel tube is widely used as a building structure. For concrete added with expanding agent, certain stresses will be produced during the solidification process. This is due to the fact that concrete solidification can not be conducted freely by the constraints of the steel tube. An algorithm of computational procedure for concrete chemical solidification stresses has been proposed, and an incremental calculation formula is derived in this paper. In addition, a testing facility has been designed and conducted to measure the circumferential strain during the solidification process. The calculation results are in good agreement with experimental data. The results show that the chemical solidification stress of concrete filled steel tube is not only related to the geometrical size of the structure and expanding rate of the concrete, but also related to the time history of expansion process. It is found that the stresses will become larger if the concrete expansion occurs later under the condition of identical expansion rates of the concretes.