Steganalysis is a technique of finding

distilling and destroying the hiding information in stego-cover. The methods of finding the hiding information can be divided into two kinds. One finds the secret information by contrasting the original cover and stego-cover

and the other

named blind detection does not have the originalcover for contrasting. The original cover for secret communication usually can' t be obtained

so the blind detection is widely adopted. In order to give an outline of the research work of steganalysis and compare the advantages and disadvantages of various methods available now

some analysis methods are introduced. The discrimination function test

χ2-test andRS-test are analyzed from both principle and experiment results

and comparisons of the three methods above are also given in certain aspects

such as the applicability and effectiveness of tests. The thresholds ofRS-test are selected at the condition of minimizing the ratio of missed detection while keeping the number of false accusations reasonable.