The invention discloses a nuclear power plant reactor loading and unloading state simulation system and method. The system comprises a management module, a reactor workshop building module and a fuelworkshop building module; the management module is used for storing the historical storing states, fuel component serial numbers, related component serial numbers and reactor loading and unloading moving plans of a reactor core and a spent fuel storing water pool; the reactor workshop building module is arranged in a reactor workshop building, the fuel workshop building module is arranged in a fuel workshop building, and the reactor workshop building module and the fuel workshop building module are used for reading data in the management module and calculating the initial states of the reactorcore and the spent fuel storing water pool before loading and unloading; in the initial states, the reactor loading and unloading moving plans for loading and unloading are read and executed from themanagement module, and the states of the reactor core and the spent fuel storing water pool in all steps are simulated and displayed according to the loading and unloading progress; and the fuel operation states of the opposite workshop buildings are read and displayed according to information sharing of the reactor workshop building module and the fuel workshop building module. According to thenuclear power plant reactor loading and unloading state simulation system and method, accurate and quick simulation of the reactor loading and unloading process and states is achieved, and the operation efficiency is improved.