A virtual assembly model of robotic single peg-in-hole assembly environment is developed to determine contact force using ADAMS/MATLAB Co-simulation in this work. The existing dynamic models of the insertion process are incapable of replicating the real assembly scenarios due to its complicated mathematical expressions and handling variety of dynamic parameters. In order to address this problem, a co-simulation model is proposed to study the dynamic behaviour of a planar robot in executing an assembly process. Initially, the physical robotic assembly environment with 3-R planar manipulator is built in SolidWorks and it is imported to ADAMS environment for the analysis. A Cartesian trajectory for the end-effector is given as input for executing the assembly process. Since simulation in ADAMS is executed with joint values, inverse kinematic calculations of the manipulator are employed in MATLAB environment to convert the given Cartesian descriptions into their corresponding joint descriptions. Further, the joint values are properly exchanged between these different software environments using co-simulation model to simulate the intended assembly process. Besides, the contact forces at peg end are analysed under defined lateral error condition.