The invention discloses an SAR image change detection method based on an oriented difference chart. The problems that in the prior art, change information of SAR images of one area at different moments can not be accurately described, and the interference resisting capacity is weak are mainly solved. The SAR image change detection method includes the steps of 1, preprocessing two SAR images of one area at different moments; 2, respectively building a mean-value ratio difference chart and a logarithm ratio difference chart for the two preprocessed SAR images; 3, according to the thought of an oriented filter, enabling the mean-value ratio difference chart to serve as an oriented chart, enabling the logarithm ratio difference chart to serve as an input chart, and carrying out fusing to generate the oriented difference chart; 4, dividing the oriented difference chart through a mean-value cluster level set model based on local joint entropy, and obtaining the result of change direction. By means of the SAR image change detection method, interference of background area information can be effectively restrained, the change direction accuracy is improved, and the SAR image change detection method can be used for natural disaster evaluation, environment resource monitoring and urban construction planning.