Tapered semiconductor lasers are characterized by high brightness and high beam quality. With the help of the numerical simulation software Lastip, the structure of 976 nm tapered semiconductor laser was optimized. In the condition of low confinement factor Γ, the InGaAs/AlGaAs quantum wells thickness and the asymmetric waveguide thickness ratio were determined. The inject power of master oscillator(MO) and the diffraction distribution characteristics of the fundamental lateral mode coupled tapered section were analyzed. The results show that, when the operating current is 3 A and the optical confinement factors are 2%, the simulation shows the fundamental lateral mode of the optimized design has more concentrated distribution compared with the conventional 2.67 W of the single quantum well(SQW) structure. The injected optical power was increased from 2.76 W to 3.67 W. And, the diffraction distribution of the fundamental lateral mode coupled into the tapered section was more uniform, the conversion efficiency of MO of optimized structure was more stable.