A类紧定装置是机载电子设备普遍采用的安装紧固结构装置，在使用过程中经常出现紧固不牢和松动等问题，影响机载电子设备的安装可靠性。利用受力解析和零件接触面形貌分析，研究了A类紧定装置的工作过程和作用机理，分析了影响A类紧定装置紧固性能的因素，提出了减小预紧力耗损、改进安装角度和减小机构间隙等设计改进措施。仿真计算和实物试验结果表明：改进措施能够有效增加机载电子设备结构刚度和强度，提高设备安装可靠性。

A-type locking device is widely used in airborne electronic equipment.The failure to fasten the equipment often occurs during operation，which may affect the mounting reliability of the electronic equipment. We studied the working process and mechanism of the A-type locking device through mechanical analysis and contact-surface analysis，and analyzed the factors that affect the fastening performance. The measures for design improvement were put forward，such as controlling the precision of pre-tension force，improving the angle of fixing and reducing the clearance.The result of simulations and tests showed that the improvement can effectively enhance the structural stiffness and strength of the airborne electronic equipment，and improve the mounting reliability of the equipment.