For auto-body product, assembly dimensional quality evaluation using tolerance analysis method is a challenging task because there are plenty of elements impacting on the variation stack-up and propagation during assembly process. Traditional method of dimension chain generation based on tolerance charting technique can not suit the case of auto-body assembly. This paper proposed a method to generate dimension chain based on developing a jot chain model of assembly, which can be integrated with important information needed for variation analysis, such as joints types and assembly sequences. The implementation of such a procedure will contribute to rapid evaluation of body dimensional quality in the design stage.