The invention discloses an application of a venenum bufonis component, namely bufalin, in preparation of a L-type calcium channel Cav1.2 subtype blocker. The compound generates a blocking effect on a Cav1.2 type calcium channel through G-protein coupled receptor and non-tyrosine receptor dependent routes, and a Cav1.2 channel blocker containing bufalin can be constructed and used for clinically treating cardiovascular and cerebrovascular diseases.