To solve the problem of drying in walnut postharvest processing, the hot-air drying technology was applied to walnut. A specifically depth drying equipment was designed and the experiment was done. The drying characteristics of walnut were investigated under different drying temperatures (35, 40, 45, 50 ℃), air velocities (0.5, 1.0, 1.5, 2.0 m/s), and load depths (0.6, 0.9, 1.2, 1.5 m). Experimental results showed that the whole drying process occurred in the falling rate period, and the effect of drying temperature, air velocity and load depth on drying characteristics was significant. The optimal drying process was temperature 45 ℃, air velocity 1.5 m/s, and load depth 1.5 m which need 32 h to drop to 12% with wet basis moisture content. Using the gap formed between adjacent walnuts, depth layer drying was achieved.