The present paper brings the parameters of the detection fiber into Monte Carlo model, and we studied the influence of fiber optic parameters and the distance of fiber from the detector on the detected optic signal,. The simulation results show that signals are obviously different when the NA (numerical aperture) and diameter of the fiber are different respectively. With the increase in NA and diameter of the fiber, the diffuse reflectance and diffuse transmission increase gradually. However, the distance from the sample surface, to some extent, brings little influence when we control it within 1 mm. By further study of the simulation result, we found that the collection efficient of the fiber is the same in different spatial positions. And the collection efficient of strong scattering material is a constant, in spite of absorption coefficient and scattering coefficient. We can normalize the diffuse signals collected by fibers with different angular aperture β by the collection efficient. Meanwhile, this paper provided the fitting curve of the collection efficient in a certain range. For fibers with different diameters, we can get a good consistence by area normalization. Therefore, the research on the effects of the difference of the detection fiber on diffuse hyper-spectrum has great significance for practical measurement. And the detection results can be transplanted by collection efficient and area normalization when we change the actual detecting fiber.