Taking YC60-7 type excavator as the research object which backhoe working device was a opened-chain four-bar mechanism,SolidWorks software was adopted to create its three-dimensional physical model.Vector method was used to establish a dynamic model of the excavator working device and dynamic simulation was done with RecurDyn.The excavator work envelope diagram and working parameter were obtained,and the stress analysis to main articulated point was carried on.The analysis results show that the biggest mining height,excavation radius,unloading height of the work device have error in 035% compared to data provided by manufacturers.It provides basis for the optimization design of excavator working device.