A novel optical system is proposed, and it is composed of two biprisms with different bottom corners and one cylindrical lens. The technical problem that the striped regional of grating structure light generating by single biprism is so small that it cannot be applied to wide range measurement is solved. Physical processes of generating grating structure light is analyzed by geometrical optics, and relevant parameters are also calculated. The intensity distribution in different positions after system is simulated by Zemax software, and the intensity distribution with the change of system parameters, e.g. structure parameters of optical elements and relative position between optical elements, are also analyzed. The conclusion of simulation is consistent with that of geometrical optics theory. The result shows that when a plane wave illuminates on the novel optical system, the grating structure light with wide measurement area, low divergence degree and adjustment flexibulity is formed.