Abstract: In the cryptology ,the Hash function can be used in the data integrity and the news authentication as well as the digital signature，SHA-256 is one kind of Hash function which is used the most widespread. This article aims at SHA-256, We carry on the random test as well as the avalanche effect test to it with χ2 text in the statistical examination method and give the analysis discussion to the test result .Besides,we pointe out some deficiency in this algorithm.