Lots of factors have influence on the firing accuracy of automatic weapon. During firing, the movement state of gun-shoulder system can be varied due to the impulsion of powder gases and the impact of moving parts, resulting in a gunpoint being deviated from initial value to decrease the firing accuracy of weapon. The development of intelligent con-trolling gun carriage for weapon system is necessary for reflect its automatic firing accuracy objectively. An electronic mea-suring system for measuring the receiving force and movement of gun-shoulder system under initiative state is built based on the characteristics of standing non-rest automatic weapon. The constitutes of measuring system and the correction method of shoulder receiving force are described, and the mechanical admittance function of gun-shoulder system is ob-tained using dectronicaUy measured data, the modal identification of admittance functions of gun-shoulder system is made by adopting the orthogonal component method, and the key difference between the passive state and initiative state of standing non-rest automatic weapon is discussed.