The present invention provides a new crystalline form VII of agomelatine, its method of preparation, application and pharmaceutical composition. This new crystalline form offers high purity, a stable crystalline structure and good reproducibility, while its method of production lends itself well to large scale production. In terms of stability and purity, it is superior to the numerous crystalline forms which have hitherto been reported. As a result, the crystalline form VII of the present invention possesses advantages in pharmaceutical preparation.