Abstract: This paper presents a new idea by modelling the reduction of solar irradiance by the presence of effective sunspots.Based on the author's personal conservative measurement of the sunspot pictures of April 1 through July 16,1980,a comparison between the theoretical solar irradiance and the total solar irradiance measured by SMMspacecraft has been made,which shows a reasonably good agreement and high correlation (r=0.78).Moreover,the author presents further an improved model of solar irradiance variability by the presence of effective active features on the photospherie disk,which is as follows.here Au,Apu,Af and A,denote the areas of umbrae,penumbrae,faculae and the visible solar disk,respectively;θu,θpu,θf are the umbral,penumbral and facular contrast values;θfh represents the limb darkening that depends on the helioeentric-angle θ.The author also sets forth several problems that need further investigations.