Environmental education must be based on the living environment of the population and must be aimed at schoolchildren, young people, adults and all categories of inhabitants. The ecomuseum is a structure that meets this objective. The natural environment, geology, flora and fauna, the landscape are part of the community's heritage and the community is co-responsible. Based on a brief description of the ecomuseum's relationship to the environment and the diversity of methods used in several countries, an example will be chosen to deepen the practices of an ecomuseum that is intended to mediate between the environment and the population. The Ecomuseum of the Serra de Ouro Preto in Brazil will be described by its coordinator according to different themes : participatory inventory of heritage, environmental education, relationship to tourism, support for research.