Under the condition of three types of basic mechanical fits, namely clearance fit, interference fit and transition fit, the offset resistance and the ongoing resistance in assembly process are investigated on the basis of physical constraints of actual assembly and the characteristics of virtual assembly. Then, a one-point force feedback model is constructed to describe the resistances. Finally, the examples and the evaluation experiments prove that the proposed model can enhance the immersion of users in virtual environment and can effectively help users identify different mechanical fits according to force feedback perception.