In the process of modal analysis of the fuel pump regulator， it is difficult to simplify the model of highly integrated assembly and establish finite element modeling of various connection modes mainly with screw connection， which have a great impact significant effect on the analysis results. From the perspective of practical engineering application， the modal analysis method of crucial substructure verification combined with global finite element modeling is proposed. Firstly， according to the structural characteristics of the fuel pump regulator， the model is simplified and meshed. Then， the crucial substructure shell modal analysis and experimental test are carried out. In the Virtual.Lab， different connection types are modeled， such as screw connection， seal ring connection， tight connection and sliding connection， and multi-type settings are carried out to solve the transition problems of different grid element types. Finally， under the premise of ensuring the accuracy of the key substructure finite element model， the overall finite element modeling and modal characteristics research are carried out， and the feasibility of the simulation method is verified by comparing with the experimental results. The results show that the crucial substructure method is better in dealing with the finite element analysis of complex small and medium-sized structural equipment， and the connection type of the finite element model of complex structure should not be too many， otherwise the solution is not easy to be converged. Multipoint constraint （MPC） method can deal with the transition of incompatible elements efficiently， and it is suitable for models with small displacement or deformation.