According to the principle of distributed Bragg reflector (DBR), the quantum well (QW) and DBR structures are optimized. By employing Crosslight computer simulation software, the reflectance spectrum and the QW gain spectrum of vertical cavity surface emitting laser (VCSEL) are simulated, and the QW composition, width and pairs of the DBR are determined. The high quality epitaxial wafers of 850 nm top-emitting VCSEL are grown by the molecular beam epitaxy technology and processed into devices. The experimental results indicate that the lasing wavelength from the In0.075Ga0.925As/Al0.35Ga0.65As QW structure with well width of 5 nm is approximately 840 nm at room temperature, and the theoretical results obtained by Ocean Optics Spectra Suite software show that the central wavelength of the spectrum is near to 850 nm at room temperature. The results verify the correctness of the design.