The draining system plays an important role in the draining of sewage in ships.The flow and pressure pulsation generated by the draining system are the main reasons for the vibration and noise of the system.One of the keys to reduce the flow and pressure pulsation and suppress the noise is to master the characteristics of pressure pulsation.A simulation model of draining system was established by analyzing the structure principle of low-noise piston pump and the pipeline structure of draining system.An experimental platform was built to verify the accuracy of the model.Finally,the characteristics of the draining system and different factors affecting the pressure pulsation were studied based on the model.The results show that the main frequency of flow and pressure pulsation is 5 Hz and 20 Hz;the opening of valve and length of pipeline have great influence on pressure pulsation while the pump parameter has little influence;the subsequent design and optimization of the draining system should give priority to the outlet pipeline.