By using the way of single screw oil press to press walnut, the experiment of CH1500T single screw press was carried out. The preheating treatment of walnut was realized through the auxiliary preheating of pressing chamber by heating device. The yield of kernel peach was obtained under different preheating time (11 min, 12 min, 13 min, 14 min, 15 min). Oil yield, residual oil rate and acid value of oil are three common indicators (to measure the quality of oil). Therefore, the residual oil rate and acid value of oil in cake meal were obtained respectively by chemical test. The appropriate preheating time of walnut oil was obtained by comprehensive analysis of the above test data. According to the theory of inverse heat conduction problem, the temperature distribution of the inner and outer wall of the press was obtained by Ansys Workbench thermal simulation. By comparing the measured and simulated temperature of the outer surface of the pressing chamber, the error range is between - 4.263% and 8.155%, which shows that the suitable temperature range of the cold pressing of walnut can be predicted by the Ansys Workbench heat conduction simulation, and the suitable temperature range of the inner wall of the pressing chamber is 43.43~ 50.23 ℃.