This paper describes an enhanced haptic assembly simulation system, in which an optimal assembly algorithm is used to allow haptic interactions and traditional assembly sequence problems. The optimal assembly algorithm provides optimal paths for haptic guidance as well as an assembly sequence of the parts to be assembled. The performance of the given assembly schemes were simulated and analyzed using a haptic assembly system. Experimental results showed that the haptic-path sequence-guidance (HSG) mode gave the best performance improvement in terms of accumulated assembly time (28.56%) and travel distance (15.64%) compared to the unguided mode, while the sequence-guidance (SG) mode alone increased performance by 16.91% for assembly time and 11.66% for travel distance. The experimental results were analyzed by the sub-tasks of gripper selection, inter-part movement, and part assembly which showed the effectiveness of the optimal assembly algorithm.