Abstract: In order to research the drying characteristics of heat pump in deep loading mode of walnut,the effect of drying temperature on moisture content and drying rate of walnut with different thickness was studied. The walnut of"Xiangling"in shaanxi province was used as the experimental material in this paper. The moisture content,drying rate and drying uniformity were investigated under different temperatures(35,45,55 ℃),load depth(0.3,0.6,0.9 m).Based on the uniformity of drying,energy consumption and drying temperature on walnut quality,the optimal drying process parameters of heat pump through flow drying were determined as follows:drying temperature 45 ℃,wind speed 1 m/s,depth 0.9 m. The optimum drying process parameters were adopted to compare and analyze the drying performance of the heat pump through-flow drying equipment and the disc drying equipment. The results showed that the heat pump through-flow drying equipment was superior to HG-400 walnut dryer in terms of energy consumption,drying efficiency and volume utilization. Unit power consumption was 40% of that of HG-400 disc drying equipment,loading and unloading time shortened by 1.9 h,and it was only 20% that of HG-400 disc drying equipment.