The invention searches the novel micromolecule inhibitor pyrazolo (1, 5-a) miazines compounds of cyclin-dependent kinase CDK9 (cyclin-dependent kinase) through the virtual screening of a computer, biometrically measures activity thereof, and validates interaction mechanism. The invention specifically comprises the following steps: the three-dimensional crystal conformation of the cyclin-dependent kinase family member CDK9 is obtained in a way of homology modeling; and micromolecule three-dimensional database is screened with DOCK (molecular docking). The invention uses a MTT tumor cell growth inhibition test to biometrically measures the activity of the selected compounds, researches the selected compounds pyrazolo (1, 5-a) miazines with high activety in a way of molecular mechanism, validates the inhibiting effect of the compounds to the activity of CDK9 kinase, and clarifies the interaction mechanism of the compounds for inhibiting the external activity and the molecule of various malignancies such as lung cancer, osteosarcoma, oophoroma, cervical carcinoma, breast cancer, etc.