Based on the core design parameters of Hualong-1, the SCIENCE V2 code is used to model the fuel loading. At the same time, 20 inadvertent loading errors of two types of fuel assemblies with the same and different enrichment are calculated and analyzed. The calculation results show that most of the inadvertent loading errors can be found when measuring the power distribution of the reactor core during the start-up physical test, and the accident can be eliminated by re-checking the loading scheme and correcting it. In the undetected inadvertent loading errors, the majority of FΔH still meet the design limit, it does not affect the operation of nuclear power plants; only a few inadvertent loading errors have not been found and FΔH exceeds the design limit, but under normal operation conditions, it meets the corresponding safety restriction criteria, and the safety margin is large.