To improve the speed of NC machining process planning for corner box parts, the automatic recognition process of machining feature was researched, and a feature recognition method based on single feature sequence graph matching in recognition direction was proposed. According to the processing process of corner box parts, the machining feature was divided into four types of front machining feature, back machining feature, front and back machining feature, and side machining feature. The recognition process of machining feature was introduced, which included the key steps such as the recognition and suppression of hole and transition feature, the generation and decomposition of attributed adjacency graph, and the discrimination of machining feature types. The prototype system of the machining feature recognition of corner box parts was established. A corner box typical part was used to verify the validity and correctness of the proposed method.