Abstract: Considering the real fact of CARR Laboratory’s HPGe detector, the detection efficiency without standard source calibration was calculated. The detection efficiency calculated by Monte Carlo method was compared with that by numerical integration method in terms of energy and volume. After measuring the activated piece (point source) and water sample (volume source), the experimental results agree well with calculated results, validating the feasibility and accuracy of calibration method without standard source. Compared with standard source calibration experiment, this method breaks through many limitations, reduces the work of preparing standard source, saves lots of time, and also greatly broadens the application scope of HPGe detector.