In order to study the anti-explosion performance of prefabricated reinforced concrete beams connected by grouting sleeve, a numerical model of prefabricated reinforced concrete beams was established. The failure modes and dynamic responses of prefabricated reinforced concrete beams under blast loads were analyzed by using multi-material fluid-structure coupling algorithm. The effects of concrete strength, longitudinal reinforcement ratio and explosive position on the anti-explosion performance of prefabricated beams were studied. The results show that for the prefabricated reinforced concrete beam, because there is a weak interface between old and new concrete at the assembled position, the transmission performance of stress wave in the beam is weakened under the explosion load, and the impact force cannot be effectively transmitted to both sides of the beam, leading to serious brittle failure in the local area. Increasing concrete strength, longitudinal reinforcement ratio and changing explosive position can improve the anti-explosion performance of prefabricated reinforced concrete beams.