Based on Timoshenko beam theory, transfer matrix method and Receptance Coupling Substructure Analysis (RCSA), a prediction method of tool point frequency response function (FRF) was proposed. Compared with mode superposition method, the method could achieve a more accurate result of calculation and higher efficiency by avoiding the modal analysis of multisection Timoshenko beams and modal superposition truncation errors. Otherwise, it was aimed to analyze the effects of spindleholder and holdertool of interface parameter, as well as the effects of individual bearing dynamics on the toolpoint FRF. The research results show that bearing dynamics control mainly the rigid body modes of the assembly of spindleholdertool, whereas, spindleholder interface parameter mainly affects the first step elastic mode, while holdertool interface parameter affects the second step elastic mode, which provide theoretical basis and technical methods for the recognition research of interfaces parameters.