Because of the reflected field the spontaneous emission rate of an electrical dipole in semiconductor microcavity is different from that in free space.In this paper the spontaneous emission rate of an electrical dipole in an ideal plane microcavity,semiconductor microcavity with mentallic mirriors and vertical cavity surface emitting lasers (VCSEL) with distributed Bragg reflectors has been calculated by fictitious image method.Calculation indicates that in microcavity the spontaneous emission rate of an electrical dipole can be enhanced in some condition and in some cavity length the spontaneous emission rate can be inhibited.