In this paper we select 10 broad spectrum solar radiation mechanism models widely used in foreign countries and achieved recognitions, and there are separate transmittance formulas in the main atmospheric attenuation process. The transmission (TR，TO，TUM), direct radiation, and diffuse radiation by selected models in relation to the exact spectrum model SMARTS are compared and reviewed strictly in an ideal atmosphere. On this basis, we then selected the model of high precision METSTAT, and corrected its defects and inadequacies regarding optical mass, transmission rate of ozone absorption and uniformly mixed gas absorption transmittance of the model, then an improved solar radiation model METSTAT_M in an ideal atmosphere is obtained. After a rigorous comparison, it is demonstrated that the METSTAT_M model is superior to other models.