Abstract: A pulse tube refrigerator to obtain high cooling power at liquid nitrogen temperature is designed.By examining thermodynamic behavior of gas elements at the pulse tube cold end,the heat exchanger at the cold end of refrigerator is found to be very important for the purpose of high cooling power.Therefore, a new kind of cold end to improve the performance of the pulse tube refrigerator is designed. The experiment apparatus is set up and a cooling power of 35 W at 80 K with 3 kW compressor is obtained.