To measure the bandwidth of a digital closed-loop accelerometer, the electricity simulation method in GJB1037A-2004 was investigated. First, some drawbacks of measuring the bandwidth of the digital closed-loop accelerometer by using the electricity simulation method in GJB1037A-2004 were discussed. Then, the detection circuit and the closed-loop control system of the digital closed-loop accelerometer with an excitation signal were analyzed. The analysis shows that the effect of excitation signal added into a feedback circuit is equivalent to an input analog acceleration in the input end and the dynamic model of the digital closed-loop accelerometer is consistent with the dynamic model of the traditional mechanical system. Finally, a method which adds the excitation signal at the feedback circuit of the digital closed-loop accelerometer to measure the bandwidth of the accelerometer was proposed. Experimental results indicate that the -3 dB bandwidth data of the digital closed-loop accelerometer is about 320 Hz, which is close to theoretic data (345 Hz). The proposed method has the features of higher accurate, less error sources and convenient to test in online ,and can satisfy the bandwidth testing requirement of most digital closed-loop accelerometers.