Abstract: This research was advocated in order to assess the performance of the delayed neutron detection system of China Experimental Fast Reactor (CEFR). Based on the structure and principle of the CEFR delayed neutron detection system, a calculating model of the delayed neutron detection signal was proposed. According to the model, a simulation program on computer was developed and some calculations were carried out in different working situation. The temperature and burnup’s effect on the detection signal was analysed. Through this research work, it can be concluded that the delayed neutron detection system of CEFR basically meet the demand and the transient simulation result will help better understand the release mechanism of fission products and the detection principle of the delayed neutron detection system of CEFR.