It is quite important and complicated to simulate sequential excavation and support process effectively and reasonably in underground engineering. To solve this problem, firstly a numerical equation to calculate excavation release loads is proposed concerned with the numerical format of finite element method. And then, an approach to dynamically simulate the excavation and support construction sequentially is put forward, in adopt of the load distribution. On the basis of the distribution of plastic coefficient of the surrounding rock, the load distribution coefficient is identified. The sequential excavation problem is transformed to simple load operation through the FEM calculation. Finally, a case study is further illustrated and it is proved that the approaches could reasonably simulate the dynamic excavation and support process and the effect of support.