A large number of prefabricated components are composed of different types of houses. The on-site assembly sequence of components is also the key link of the construction organization of the project. The assembly sequence obtained by manual experience is easy to omit components and interfere with each other. According to the weight and assembly process of construction components, the evaluation index of mechanical assembly process is introduced to clarify the relationship between the number of components and the assembly process. In the aspect of intelligent optimization algorithm, the simulated annealing program module is introduced into the existing genetic algorithm to form a new simulated annealing genetic algorithm. The comparative study of the calculation results shows that the simulated annealing genetic algorithm can search the global optimal assembly sequence scheme more accurately and efficiently, and meet the evaluation indexes at the same time. The mechanical simulation technology is innovatively used to simulate the assembly of building components, and the simulation process is used to guide the on-site construction process.