Provided are a pharmaceutical composition of a substituted pyrazolo[1, 5-a]pyrimidine compound and the use thereof. The substituted pyrazolo[1, 5-a]pyrimidine compound is a compound as shown in formula (I), or a pharmaceutically acceptable salt, prodrug, hydrate or solvate, polymorph, stereoisomer or isotopic variant thereof, and can be used for treating diseases treatable with Trk kinase inhibitors.