An improved algorithm of tooth contact analysis (TCA) is proposed to overcome the deficiency of the current TCA algorithm for hypoid gear. The key improvement of the proposed algorithm is to introduce proportional coefficients of tooth length and tooth height in TCA. The solution domain of the nonlinear equations in TCA is limited in the range of tooth surface by variable substitution. By analyzing the positions which boundary points possibly appear on axial section, the values of proportional coefficients corresponding to the positions are obtained. Boundary points of the contact trace are computed with particle swarm algorithm and conjugate gradient method, and distributed points on the contact trace are solved according to information of boundary points. With the improved algorithm the boundary points of the contact trace can be figured out accurately and there is no need to set initial values for tooth contact analysis.