Abstract: Cracks are mostly in mixed mode in practical engineering. For mixed mode crack, it is key to determine its initiation angle and critical load. Combining the minimum normalized plastic zone size and the strength theory of generalized composed deviator stress, this paper proposes a fracture criterion of the mixed mode crack in brittle material to predict the initiation angle and critical load. Comparing the results by the proposed criterion with those of the maximum stress criterion and strain energy density factor criterion, it is found that the critical load curve by the proposed criterion is greater than that of maximum stress criterion and it is close to that of strain energy density factor criterion. Therefore, the proposed criterion is effective for predicting the initiation angle and critical load.