The reactor trip breaker is an important executive mechanism of the emergency reactor shutdown system in a nuclear power plant, and its control signals are provided by the reactor protection system. In the factory testing phase of the reactor protection system, to verify the correctness and effectiveness of the reactor shutdown function of the reactor protection system, a simulation apparatus of the reactor trip breaker is needed to receive the control signals of the reactor protection system and feedback the status signals of the reactor trip breaker. Taking the protection function verification during factory testing of an HPR1000 safety-class DCS from China National Nuclear Corporation as an example, this paper designs models of the reactor trip breaker constructed by using relays and virtual instrument technology respectively in the factory, analyzes the advantages and disadvantages of these two schemes, and connects them to the reactor protection system to conduct protection function tests. The test results demonstrate that both schemes can accurately simulate the logical functions of the reactor trip breaker and assist in completing the functional tests of the reactor protection system. Compared with the reactor trip breaker simulation system constructed based on relays, the reactor trip breaker simulation system based on virtual instrument technology possesses the advantages of flexible configuration, simple circuit construction, complete signal simulation, ease of use, and convenient maintenance.