Abstract: To avoid inaccurate predicted values of zero power physics test (ZPPT) parameters, which will affect the commissioning and startup of the nuclear power plant, the numerical reactor can be used to accurately predict the ZPPT parameters. Based on the codes of the CAP1400 numerical reactor system, including the Monte Carlo code JMCT, the deterministic high-fidelity code NECP-X and advanced neutronics code SCAP-N, the CAP1400 first core was modeled to realize high-fidelity simulation of the ZPPT parameters. Numerical results show that the calculation results of the three high-fidelity simulation codes are in good agreement. Taking JMCT as a reference, the absolute deviations of NECP-X and SCAP-N for the gray control bank worth are within ±8×10⁻⁵, the relative deviations for the black control bank worth are within ±3%, the relative deviations for the total worth of all the black control banks are within ±1%, and the relative deviations for the assemble relative power are within ±2.5%. The ZPPT parameters of the CAP1400 first core are accurately predicted, which can effectively support the commissioning and startup of the CAP1400 reactor.