Considering that impact load in the process of tray lifting device and unstable pressure from cylinder can cause frequent structural failure on the junction between sensor and tray, molding of the lifting device is carried out through Three Dimensional (3D) PROE software. Modal and harmonic response analysis of the device was carried out based on ANSYS Workbench software. The relationship between the weight loading position and the inherent frequency of tray lifting device was researched. From harmonic response analysis, the effects between different loading methods were researched on the tray and the amplitude frequency curve of the junction, finding the modal order that easy to resonate through inherent frequency line chart and determining the resonant frequency might occur on the lifting device based on the amplitude frequency curve. To sum up, research can provide certain theoretical references to avoiding resonance phenomenon of tray lifting device in the actual work.