The present disclosure relates to novel crystalline forms of ozanimod and preparation method thereof. The provided crystalline forms of ozanimod comprise crystalline form CS9, crystalline form CS10 and crystalline form CS11, and can be used for treating autoimmune diseases, particularly used for preparing drugs for treating multiple sclerosis and ulcerative colitis. The crystalline forms of the present disclosure have one or more advantages in solubility, stability, hygroscopicity and processability and provide new and better choices for the preparation of ozanimod drug product, and are very valuable for drug development.