This study was proposed to solve the problems of low efficiency and poor safety of tunnel arch installation under complex conditions. Based on the difficulties of traditional arch construction, this paper develops mechanized equipment such as high degree of freedom arch main installation machine and auxiliary installation machine and assembly supporting devices suitable for mechanized construction and forms the mechanized construction technology of assembly arch. The results show that the fabricated construction method is of great significance in improving the initial strength of the arch frame; the rapid formation of the arch frame bearing system is the key to ensuring the effective control of the elastic-plastic deformation of the surrounding rock. Based on the above research, the results have been preliminarily applied in the reconstruction and expansion of Magongci tunnel of Binlai expressway, the construction efficiency has been significantly improved, and the surrounding rock deformation has been effectively controlled.