Abstract: MCCOOR code was used to simulate the nuclide compositions for pressurized water reactor(PWR) fuel and boiling water reactor(BWR) fuel in the pin-cell model at different burnups for two different initial fuel enrichments and full power history, respectively. By analyzing the correlatednuclides ratios of light-water reactor(LWR) fuel, the characteristic ratios of correlated-nuclides for LWR fuel were found, and the characteristic ratios of related nuclides for spent fuel can be used to identify the reactor type.