Secret message can be embedded into letters in tags of a webpage in ways that are imperceptible to human eyes viewed with a browser. These messages, however, alter the inherent characteristic of the offset of a tag. This paper presents a new higher-order statistical detection algorithm for detecting of secret messages embedded in a webpage. The offset is used to build the higher-order statistical models to detect whether secret messages hide in tags. 30 homepages are randomly downloaded from different websites to test, and the results show the reliability and accuracy of the statistical characteristic. The probability of missing secret message decrease as the secret message increase, and it is zero, as 50% letters of tags are used to carry secret message.