In order to detect the malicious modify, so called hardware Trojan, a power consumption model was set up in this paper based on the side-channel analysis. Using the Euclidean and the Mahalanobis distance discriminaiton to achieve the detection and discrimination of hardware Trojan, compared the speed and accuracy of the two methods, then chose the better one to construct a classifier. Experimental results shown the classifier was able to identify the circuits with a Trojan occupied 1.49% of AES module.