Abstract: The present disclosure provides a class of 2-aminopyrimidine compounds with a structure shown in Formula (I) or their pharmaceutically acceptable salts, isotope derivatives, solvates, or their stereoisomers, geometric isomers, tautomers, or prodrug molecules or metabolites and pharmaceutical compositions and application thereof. The compounds of the present disclosure can efficiently and selectively inhibit the kinase activity of Janus Kinase 3 (JAK3), and have strong signal inhibition and cell proliferation inhibition effects on various blood tumor cells (especially human acute myeloid leukemia cell U937 cells) and solid tumor cells. They can be used to prepare anti-tumor drugs and drugs for preventing and treating inflammatory diseases.