:In this paper,we introduced the dressed exciton model of the semiconductor micro cavity device.In the semiconductor quantum well(QW) of vertical cavity surface emission (VCSE) device,the excitons first coupled to the cavity through the intra electromagnetic field and formed the dressed excitons.Then these dressed excitons decayed into the vacuum cavity optical mode,as a multi particles process.Through the QED method,the dipole emission density and system energy decay equation were obtained.From the discussion of the solutions in three regimes,the superradiation and anisotropic decay rate were well understood.