The scattering ability of light guide plate (LGP) dots directly affects the light energy utilization and dot density of backlight module, so quick selection of the best dot structure is very important for manufacturers. This paper proposed a method to evaluate the effective light guiding ability of dots by LGP dot scattering efficiency. Based on the LGP dot density file that has been mass-produced by the manufacturers, the influence of the dot inclination angle on the scattering efficiency was studied theoretically and experimentally, and the best dot structure obtained was applied to actual processing. The results show that the method can reveal the correlation among the dot scattering efficiency, the light energy utilizaiton rate, the effective light-emitting area and the dot density. An inclination angle range of 25°--60° corresponding to the maximum light energy utilization rate can be obtained. In this range, the dot scattering efficiency and inclination angle are positively correlated. By re-optimizing the LGP uniformly with dots with higher scattering efficiency, it is found that the number of dots could be reduced by 60%, the light energy utilization rate is only reduced by 2%, and the actual machining effect of LGP is consistent with the simulated effect.