Based on the energy band theory and the principle of distributed Bragg mirror (DBR), the reason for the large DBR series resistance in VCSEL was analyzed. The potential barrier at the interface of heterojunction in DBR structure was reduced by component gradient, the doping concentration of each layer of DBR was optimized, and the heterojunction potential barrier in DBR was further reduced by regulating Fermi energy level, thus the series resistance of DBR was effectively reduced. Al0.22Ga0.78As/Al0.9Ga0.1As was used as two materials for DBR growth. The thickness of each layer of DBR was designed and the optimum growth temperature of AlGaAs material was studied. The 795nm VCSEL mutation DBR and gradual DBR were grown by MOCVD epitaxy. The resistance of mutant DBR and gradient DBR was 6.6 and 5.3Ω, respectively. The resistance of DBR after optimized growth was effectively reduced.