Today, parallel with the rapid increases in population, waste production is also increasing that together with decreasing availability of proper land for landfill sites has created a complex management issue despite the progresses in science and technology. Composting is a useful way of waste management that has many environmental and economic benefits, but compost plants can also have significant impacts on the environment. Hence, selection of suitable locations for landfill and compost plants is one of the important issues in waste management program. Mathematical matrices in association with geographic information system (GIS) are used as a strong approach to EIA of compost sites and their selection. In mathematical matrices, important criteria for site selection of compost plants are studied. Then, effects are assessed in GIS and their significances are determined. In mathematical matrices, impacts significance are calculated using 7 factors including magnitude, extent, duration, synergistic effects, accumulative effects, controversy and mitigation measures, based on which appropriate site for compost plant is selected. In the present study, Golpayegan City in Isfahan Province was selected to perform compost plant site selection. The map overlay method was used to generally and qualitatively assess the impacts and the mathematical matrices method was used for impatcs quatification. Three alternatives sites were studied. According to the results, alternative 3 was the best. The second preference was alternative 2 and the third was alternative1. This approach has flexibility through inclusion of compensation criterion and controversy which help in bringing about consensus among proponents and EIA assessors and therefore, will create more comprehensive results.