The analysis of environmental conflicts is of vital importance to verify the viability and analyze the impact of projects in environments with a social presence The grey systems facilitate the obtaining of knowledge in environments that are not very clear or with little information and the diffuse logic allows through linguistic variables and fuzzy sets to represent the conceptual knowledge in the computer and the IF-THEN rules allow to make the inference based on those concepts and give conceptual results easily accessible to people. In this paper we propose a approach to develop systems based on knowledge using grey systems and fuzzy logic for analysis of environmental conflicts during all phases of projects A test is carried out using the case study data in [1] of a mining project in northern Peru and a knowledge-based system that can be used for the analysis of environmental conflicts during all phases of the project or for analysis in environments with similar characteristics is implemented.