Discloses is a method for calculating single rod power of an overall reactor core. The method includes steps of 1), determining geometrical and material parameters of a target
nuclear reactor according a reactor core structure thereof; establishing an SP3 equation set of step 0 or step 2
neutron angular flux
torque density according to a multigroup
neutron transport theory; 2), adopting structural grids to subdivide
structural geometry zones with corresponding shapes, and unstructured grids to subdivide unstructured geometry zones; 3), establishing a segment SP3 method, subjecting the SP3 equation set in the step 2) to numerical discretion by adopting approximate
processing modes which are mutually compatible under a structural grid and the unstructured grid, and acquiring
neutron-flux density on all grids of the
nuclear reactor core by utilizing iterative
algorithm to solve discrete
algebraic equation set; 4), adopting the neutron-flux density acquired in the step 3) to calculate the single rod power of the overall reactor core. By reducing approximation from grid
subdivision, approximation from the numerical discretion and iterative calculation process and approximation from component homogenization and component power reconstitution, the high-precision single rod power of the overall reactor core can be calculated.