The optical properties and differences for normal human stomach mucosa/submucosa tissues in vitro at 488 nm, 514.5 nm, 532 nm, 630 nm and 632.8 nm wavelengths of laser were determined in this paper. Measurements were performed using a charge coupled device (CCD) detector, and optical properties were assessed from the measurements using the spatially resolved reflectance, and nonlinear fitting of diffusion equation. The results of measurement showed that absorption coefficients, reduced scattering coefficients, optical penetration depths, diffusion constants, diffuse reflectance and shifts of the diffuse reflectance of the tissue samples at five different laser wavelengths vary with a change of laser wavelength. The maximum absorption coefficient for tissue samples is 0.482 mm-1 at 532 nm, and the minimum absorption coefficient is 0.224 mm-1 at 632.8 nm; the maximum difference in the absorption coefficients is 115% between 532 nm and 632.8 nm, and the minimum difference is 1.90% between 488 nm and 532 nm. The maximum reduced scattering coefficient for tissue samples is 5.93 mm-1 at 488 nm, and the minimum reduced scattering coefficient is 3.87 mm-1 at 632.8 nm; the maximum difference in the reduced scattering coefficients is 53.2% between 488 nm and 632.8 nm, and the minimum difference is 3.25% between 514.5 nm and 532 nm. The maximum optical penetration depth for tissue samples is 0.612 mm at 632.8 nm, and the minimum optical penetration depth is 0.341 mm at 488 nm. The maximum diffusion constant for tissue samples is 0.084 mm at 632.8 nm, and the minimum diffusion constant is 0.055 mm at 488 nm. The maximum diffuse reflectance for tissue samples is 0.356 at 630 nm, and the minimum diffuse reflectance is 0.271 at 532 nm. The maximum shift of the diffuse reflectance of the oblique incidence for tissue samples is 0.153 mm at 632.8 nm, and the minimum shift of the diffuse reflectance of the oblique incidence is 0.100 mm at 488 nm. It is obvious that there were distinct differences in the optical parameters for normal human stomach mucosa/submucosa tissues at five different laser wavelengths.