Cloud is an important factor for the radiation budget through reflection of solar radiation and absorption of terrestrial radiation. Climate change is dependent on these two effects and focusing on an aerosol-cloud interaction. In East Asian region, consumption of fossil fuels is increasing and emits many kinds of gas and particles in addition of natural sources. The indirect effect of aerosol depends on the aerosol characteristics and weather conditions. The particle size and chemical features of aerosols affect cloud formation and particle size. Therefore, it is interesting to understand cloud properties such as a liquid water path (LWP) and cloud effective radius (Reff). This study is to estimate these two parameters with ground-based observations. In the paper a method to estimate a cloud effective radius and optical thickness is proposed using a combination of corrected LWP and the downward solar radiation. It is useful for continuous observation, especially LWP can be estimated for all day.