Based on the piezoelectromagnetism theory, the dynamic problem of a crack of finite length embedded in a polarized ceramic under the action of antiplane mechanical impact and inplane electric impact is considered. The basic equations are simplified to two decoupled wave equations. Integral transform techniques are employed to reduce the associated initial-boundary value problem to integral equations. By using numerical methods, the resulting integral equations are solved and dynamic field intensity factors are presented graphically. A comparison of the dynamic results and the quasi-static results for dynamic field intensity factors near the crack tips is made, and the effect of mechanical impact on the dynamic magnetic field intensity factor is examined.