The analytical expressions for the phase shift on reflection of Distributed Bragg Reflectors (DBRs) with odd and even numbers were derived based on the transfermatrix method.The expression for the penetration depth of DBR as a function of phase shift was given according to the relationship between the phase shift and the reflection delay.The DBR with the structure of［HL］2H was fabricated by electron beam evaporation and the transmittance spectrum,and phase shift and penetration depth were measured or simulated.The microcavity organic light emitting diode (MOLED) was fabricated using the designed DBR.The measured effective cavity length of the MOLED fit well with the calculated one.