Aiming at the problem that it is difficult to generate the dynamic decoupling equation of the parallel six-dimensional acceleration sensing mechanism， two typical parallel six-dimensional acceleration sensing mechanisms are taken as examples. By analyzing the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism， a new method for establishing the dynamic equation of the sensing mechanism is proposed. Firstly， based on the scale constraint relationship between the hinge points on the mass block and the hinge points on the base of the sensing mechanism， the expression of the branch rod length is obtained. The inherent constraint relationship between the branches is excavated and the branch coordination closed chain of the “12-6” configuration is constructed. The output coordination equation of the sensing mechanism is successfully derived. Secondly， the dynamic equations of “12-4” and “12-6” configurations are constructed by the Newton-Euler method， and the forward decoupling equations of the two configurations are solved by combining the dynamic equations and the output coordination equations. Finally， the virtual prototype experiment is carried out， and the maximum reference errors of the forward decoupling equations of the two configuration sensing mechanisms are 4.23% and 6.53%， respectively. The results show that the proposed method is effective and feasible， and meets the real-time requirements.