Abstract: A two node method is developed to solve the fine mesh SP3 equations. The Laplace operator on the 0th moment flux is treated by nodal method. The transverse integrated 0th moment flux is expanded to a second order polynomial, and the transverse leakage term is approximated with flat distribution. A prototype code named CORCA-PIN is developed for the fine mesh whole core transport calculation. And fine mesh finite difference method is implemented in CORCA-PIN. KAIST 3A benchmark problem and extended 3D problem are tested. Numerical results show that an acceptable accuracy is achieved using the two node method with 1by1 mesh per cell. Meanwhile, the time is 12% of the fine mesh finite difference method with comparable accuracy. The two node method proposed in this paper is suitable as the solver of fine mesh SP3 neutron transport equations.