The present invention relates to a deuterated phenylamino pyrimidine compound and a drug composition containing the deuterated phenylamino pyrimidine compound. Particularly the present invention discloses a deuterated phenylamino pyrimidine compound represented by a formula (I), and a drug composition containing the deuterated phenylamino pyrimidine compound, or a crystal form, a pharmaceutically acceptable salt, a hydrate or a solvate thereof. The compound can be used for treating and / or preventing JAK kinase-associated diseases such as myeloproliferative diseases, cancers, immunologic diseases and the like.