The invention discloses a nuclear power station loose part monitoring system. Monitoring objects include a pressure container and a steam generator connected with a steam tube bundle. The nuclear power station loose part monitoring system comprises first acceleration sensors, a second acceleration sensor and third acceleration sensors, two first acceleration sensors are symmetrically arranged on a generator shell perpendicularly above and below a pipe plate on the primary side of the steam generator, the second acceleration sensor is arranged on the generator shell and near the top end of the steam tube bundle, and the three third acceleration sensors which are positioned in the same one circumference and mutually have 120-degree angle are arranged at the bottom, at the top and the upper middle part of the pressure container, respectively. The monitoring area of the steam generator and the pressure container are covered by the monitoring points of the nuclear power station loose part monitoring system, the problem that the monitoring point position in the prior art cannot meet the standard requirement is solved, the monitoring is complete and the accuracy is high, and the nuclear power station loose part monitoring system is applicable to the high-performance index requirement of existing reactor type.