Abstract: The formula of the deviation angle is deduced. The influence of the prism angle and the refractive index on the relationship between the angle of incidence and the angle of refraction are discussed. The angle of inclination and the angle of incidence are discussed. The relationship between the vertex angle and the refractive index，and the physical meaning of the curve are expounded. Finally，the minimum deflection angle is studied.

Key words: prism, total reflection, deflection angle, specifications, matlab