天幕靶探测灵敏度是天幕靶重要的性能指标。分析了天幕靶的工作原理和灵敏度机理，给出了光学镜头参数、被测弹丸长度与灵敏度之间的关系公式，提出了一种用小口径弹丸标定灵敏度的方法，推导了倍弹径数标定修正公式。通过气枪弹试验验证，文中研究的标定方法可行，给出的倍弹径数对实际使用具有明确的指导意义。

The detection sensitivity is an important performance index for sky screen target. Working principle and sensitivity mechanism of the sky screen target are analyzed. The relation formula of optical lens parameters, measured bullet length and sensitivity are given, a method to use the small caliber bullet to determine the sensitivity is presented, and the modified formula of caliber bullet is derived. The air gun bullet experimental tests verify that the calibration method is feasible, and the given caliber bullet has a guidance significance in application.