¡@Because the public take account of ecological and environmental protection, there are many conflicts between the public and constructors to trigger many obstacles and duels in construction of many infrastructures. Thus, tradeoff between environment, lives, property and economic benefits is a big problem. In the researches of plural public affairs decision making and cognition impact management problems, practical researches found that Hammond(1965, 1975, 1996) developed SJT(Social Judgement Theory) from Lens model and had significant effects and contributions for analysis of public affairs decision making. The thesis uses SJT and studies cognition conflict management on representative case of environmental protection ¡¥the construction of CPC Yung-An LNG¡¦ in Taiwan. ¡@CPC Yung-An LNG began construction in May in 1984. Because environmental consciousness rose, the public gave relief to themselves when encountering environmental pollution. Negligence of communication with the village and of good-neighborliness makes the village not make allow and trigger Yung-An village dueled. This study bases on economic environment, gathers relative literatures and presents four controversial and representative topic for decision variables. They are individually ¡¥X1(benefit of construction of the firm)¡¦ and ¡¥X2(subsidies for the residents)¡¦ for economy, ¡¥X3(threat for ecology and environment)¡¦ for environment and ¡¥X4(threat for lives and property)¡¦ for both economy and society. ¡@This study uses SJT on the construction of ¡¥CPC Yung-An LNG¡¦ for cognition conflict management. The results are as below: (i)Government has higher stability and consistency of making decision than the residents. (ii)Government and the residents have significant difference for weight mean values of X1, X2 and X4. And they are the conflicts between them. (iii)Men and women have no significant difference for weight mean values of all decision variables. (iv)The older deciders have higher emphasis on X3 than the younger. But they have no significant difference for weight mean values of the other decision variables. (v)Lower educational background deciders have higher emphasis on X4, and there is no significant difference for all the other decision variables. (vi)There is no significant difference for weight mean values of all decision variables between core and border area. ¡@Finally, the study gets the judging principles of government and the residents. They are ¡¦average weights¡¦ and ¡¥function types¡¦ of all decision variables. Then, we use ¡¥specify¡¦ on Policy PC 3.0 software to make estimated judging table for all decision situations for government and the residents. Looking into the table can estimate the acceptance of government and the residents for all combinations of decision variables when making policies. We also can use the table to estimate the change of acceptance of government and the residents when any decision variables improve, and the authorizations can use the resources for the most efficient and effective applications when proposing improving methods.