The main purpose of this study is to propose the integrated assessment model for the rational and effective selection of proposed sites in National Trust(NT)and conserve the ruined natural environment by excessive land development. The results of this study are as follows; 1)The specialists thought that rare and endangered species were very important in plant and animal, in case of landscape and environment, naturality and water quality were too important. 2)In the result of the correlation measure on the imdicator of assessment,`erosion of soil`and `air pollutant` was highly correlative, Secondlt,`suspended solids` and `erosion of soil`was high correlation. 3)In the results of forming the factors into the integrated indicators, they were classified in conditional,stable,valuable and potential factors and the pupose of this formation is to evaluate proposed sites in NT objectively and rationally with organic assessment. 4)In the integrated assessment model, the degree of explanatiion was observed approximately 36.4% and the important factor was the conditional factor, but we have to consider all factors for the effective assessment. therefore we organically have to apply and use them for the assessment of proposed sites in NT. IT turns out to offer rate data on the land conservation and carry out the role of the instrument of measurement. As for furture, the follow are proposed:1)adaptation of real proposed site ,2)verfication of effect and problem,3)practical survey for dicerse tupes as mountain, coast and inland.