Abstract: Critical boron concentration and burn-up calculations are the basic function for the reactor nuclear design software. Three-dimensioned few-group neutron calculation software CORCA-3D was developed by NPIC on self-independence, with full intellectual property rights, and it can be applied to the nuclear design and analysis. The theory of critical boron concentration and burn-up calculations in CORCA-3D is introduced in this paper, and the functions are validated with benchmark problems, measured data and the SCIENCE system. Results show that CORCA-3D is with high accuracy.