The invention discloses an LSB replacement steganalysis method based on grey co-occurrence matrix statistic features. The method includes the steps of image bit plane decomposition, grey co-occurrence matrix calculation, feature selection and extraction and classification. Firstly, a grey image is decomposed into eight bit planes, differential matrixes between the lowest bit plane and other seven bit planes are respectively calculated, then a sum matrix of the differential matrixes is calculated, a grey co-occurrence matrix of the sum matrix is generated, the obvious features are extracted and calculated by researching and analyzing the characteristics of the co-occurrence matrix, and a support vector machine is used as a classifier to distinguish carrier images and hidden images. According to the method, the number of feature dimensions is small, curse of dimensionality is effectively avoided, detection precision is high, an algorithm is stable, robustness of image processing of retaining operations of JPEG compression, median filtering, noise addition and the like is achieved, satisfying generalization ability is achieved, and calculation complexity is low.