Through risk assessment process, it is necessary to identify, analyze, and prioritize systematically all environmental impacts of industries which have high destructive potentiality as well as representation of a mitigation plan. The current study aims at identification and prioritization of risks and impacts caused by Abadan Gas Power Plant. All kinds of the operational risks of the power plant were identified using 99 DELPHI Questionnaires filled up by expertise and proficient. Afterwards, in order to risk prioritization of each unit existed in Abadan Gas Power Plant TOPSIS Method was applied as one of the Multi Attribute Decision Making (MADM) methods. The mentioned method is widely applied in risk assessment studies due to its usefulness in straightforward application of expertise's intrinsic perceptions in model as well as achieving more objective results in risks analysis and prioritization. The relative importance of criteria was obtained at third step of TOPSIS using Shannon Entropy and Eigenvector Techniques. Subsequently, after risks prioritization of each unit separately, the most important risks of Abadan Gas Power Plant were determined using TOPSIS Method and one-way analysis of variance (one-way ANOVA) statistic test. The calculated results of Abadan Gas Power Plant risk analysis revealed that risks derived from activities including unit commissioning with weight of 0.807, fuel tanks with weight of 0.798, gas fuel delivery with weight of 0.630 as well as working on the cultch of the liquid fuel with weight of 0.603 and replacement of gas filters at mechanic unit are the most important environmental risks of the power plant. Therewith, strategies to control and mitigate the identified risks were presented. Among the suggested strategies, usage of electrical protective and intermittent equipments, periodic visits and preventive repairmen against fire and exploitation risk of the power plant can be noted.