A solid model of rotary mechanism for boom type roadheader was built by means of UG software. The solid model was introduced into the ADAMS through the interface of the UG solid model and the ADAMS and a simulation model of machinery-hydraulic coupling system of boom type roadheader was established. Dynamics simulation was carried out. Force curves of the rotary cylinder and the lift cylinder to the rotary table joints under different positions were obtained. The relationship between the axial force and radial force in the same period was analyzed. Research results could improve the stability of boom type roadheader working process and provide a strong theoretical basis for the further optimal design of the rotary mechanism.