Objective To study the changes of the primary packaging device under force. The conclusions of the paper can provide theoretical reference for China's Lunar sampling mission. Methods The composition of China's Lunardetector was discussed. The working principle of Lunar soil primary packaging device of surface sampler was analyzed. Based on the principle of soil mechanics, the relationship of tube inner diameter and soil height in the tube was revealed. Results The simulation results showed that the maximum stress was 98 MPa and the displacement of soil tube was 0.02 mm, both occurred at the bottom center of the Lunar soil packaging tube. Conclusion By establishing a force model of lunar soil in the primary packaging tube, the relation between the tube inner diameter and the height in the tube was revealed; the simulation analysis suggested that the stress and the displacement were the highest at the bottom center of the tube, and that the maximum stress did not exceed the yield limit of hard aluminum alloy adopted for the lunar soil tube, while the maximum displacement could be solved by the equipment tolerance.