The invention discloses a freight wagon blocking key missing fault identification method based on a support vector machine, and belongs to the field of freight wagon running fault testing. The freight wagon blocking key missing fault identification method includes a training process of the support vector machine and a process of online blocking key missing identification of the support vector machine. With the freight wagon blocking key missing fault identification method based on the support vector machine, when a train passes through, images of a running freight wagon body, freight wagon type and freight wagon information can be acquired; whether the images include the blocking key component or not can be confirmed through image naming; coarse positioning of a blocking key can be completed through positioning shaft ends so as to further complete fin positioning of the blocking key;HOG (Histogram of Oriented Gradients) features of blocking key images are extracted, and blocking key identification classifiers are inserted to complete blocking key missing fault identification. With the freight wagon blocking key missing fault identification method, training samples can be conveniently added, and corresponding classifiers can be trained based on different detection stations. The freight wagon blocking key missing fault identification method can be run automatically without mannual interference, running parameter can be controlled through configuration files; identification speed is fast, and automatically identified results can be stored in a friendly mode so as to facilitate verification and review of the identified results by train examination staff.