To overcome disadvantages of modeling application and uncertainties of the reliabilities of the existing LED light source model and others, the reliability of light source modeling was studied for distribution design on compact LED. By optimizing different models with different lens and LED diameters ratio, the difference of three modeling methods including point light source model, surface light source model and ray-file light source model in the system was compared and analyzed. Taking the ray-file light model as the standard, an optimal design and analysis computation of the optical element were carried out when the beam angle was ±15°, ±10°, ±5° for different lens and LED diameter ratio, by choosing the conventional compact total-reflection lens as the second optical element and using three modeling methods including point light source model, surface light source model and ray-file light source model. Experimental results indicate that surface light model can take place of the ray-file light model when the deviation of utilization of energy is within ±2%, the beam angle is ±15° meanwhile lens and LED diameter ratio is more than 36∶2. It happens too when the beam angle is ±10° while the lens and LED diameter is 44∶2. In the case that the beam angle is ±5°, and the lens and LED diameter ratio is 82∶2, the ray-file light source model can also be taked place by the surface light source model. However, the ray-file light source model cannot be replaced by the point light source model in any case when the deviation range falls into ±2%. The results provide basis for the system design and solve the problem of time wasting of assisting optimal design by using ray light source model, which will be of great benefit to the future research.