Abstract: The optimized design of PDC bit for directional drilling and steering performance analysis need accurate calculation of cutting parameters like cutting area, cutting volume and cutting arc length of PDC cutting teeth. In line with different drilling tools-bent housing screw motor or pushing rotational steering system, this paper analyzed the motion status of PDC bit at bottom hole, established the trajectory of cutting teeth and cutting curvilinear equation. Also the numerical computing method was established for cutting area, cutting volume and cutting arc length of the cutting teeth according to bit deflection angle, complex bit motion, bit structure parameters and the sequence of cutting teeth, providing a analysis method for computerized optimal design of PDC bit and the analysis of steering performance of PDC bit. Practical calculation shows that the model and method are practical and can be further promoted.