Abstract: The optimization of hydraulic structures for PDC drill bits is an effective means to control the generation and development of bit balling. The physical model of PDC bit with a lateral jet nozzle is established, based on computational fluid dynamics theory and the problem that the PDC bits is easy to encounter balling when drilling. Numerical simulation on the flow is done by solving the closed N-S Equation with turbulence model and SIMPLIC procedure, and the characteristics of the flow field at the bottom and velocity, pressure distribution on the blade surface are studied qualitatively. The results show that the new jet area formed by lateral jet minishes the coverage area of vortex at the bottom, and it plays an active role in cleaning the bottom; driven by the lateral jet, shear stress and pressure difference increase on cutting surface, which helps inhibit the growth of balling and cooling blade to improve bit performance. This provides a new way of thinking for the optimization of hydraulic structures for PDC bits.