Three alternative efficiency calibration methods were introduced and employed to calculate the efficiency curve for detecting a simulated gas source with known activity by a HPGe detector .The dimension parameters of the model utilized by Monte Carlo (MC) method were based on the parameter values supplied by its manufactory .The result of MC method is unreliable and its maximal relative deviation reaches 130%compared with the experimental results .Both numerical integration (NI) method and representative point (RP) method utilized a multi‐γpoint‐like standard source as well as MC simulation .When the energy range of γ‐ray is 60‐1 836 keV ,the relative deviations of RP method are within ± 6% while those of NI method are within ± 4% .The NI and RP methods satisfy the uncertainty requirement in field work ,while RP method is much easier to be implemented .%介绍了3种替代的效率校准方法，并分别用它们计算1台HPGe谱仪测量1枚等效气体源时的探测效率曲线。蒙特卡罗（M C ）法建立的探测器模型中所用尺寸参数为厂商提供的值，其计算结果不可靠，与实验值的最大相对偏差达130％。数值积分法和代表点法皆用了1枚多γ核素标准点源，同时还借助了M C模拟计算。当γ射线能量在60～1836 keV范围时，代表点法计算结果的相对偏差≤±6％，数值积分法计算结果的相对偏差≤±4％，这两种方法均能满足现场工作对不确定度的要求，其中代表点法更易实施。
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