A silicon-based zero refractive index grating (ZCG) reflector for 940 nm vertical cavity surface emitting laser is designed by using strict coupled wave theory and time-domain finite difference method. The high reflection characteristics of ZCG are investigated, and the conditions for achieving broadband high reflection are analyzed. In addition, the effect of grating structure parameters on reflection performance is discussed and fabrication tolerances are calculated, and the effect of ZCG size and VCSEL oxide aperture size on mirror loss is simulated. The designed ZCG with a bandwidth of 280 nm, Δλ/λ0=29.8%, can replace the conventional distributed Bragg reflector in VCSELs, reduce the process difficulty and growth cost, and facilitate the integration of VCSELs with other Si-based optoelectronic devices.