Based on the mechanical force model of the bucket on the working device of loader,the problem of the dynamic loading test was analyzed. The testing method considering pin-shaft lateral dynamic force was put forward,and the 3D forces in horizontal,vertical and lateral direction of the loader working device were accurately measured. Without changing the loading characteristics of the working device,the pin-shaft dynamic force test system was established with the pin-shaft sensor design and the bucket structure modification. Primary soil containing granular iron ore was chosen as the shovel loading operation case,and the dynamic forces in three directions of the pin-shaft linking the arm and the bucket were acquired through the shovel loading test. The results show that: the dynamic testing method and the system could accurately obtain the dynamic loads of three directions of the pin-shaft; the dynamic loads of the three directions measured by the pin-shaft sensors are closely related to the loading process; the dynamic loads of the lateral force of the loader working device with the change of loading process were obtained firstly. It has important guiding roles for the study on the mechanical characteristics of the loader working device,the acquisition of the load spectrum and the prediction of fatigue life.