This work is part of a first phase of the project "DOMAIN SPECIFIC MODELING FOR THE LEARNING OBJECTS BUILD PLATFORM-INDEPENDENT " and seeks to make a comparison between Open Source LMS to get a first approximation of common modules them, and then start building the ontology compatible with all LMS studied, for that reason this paper is organized as follows: 1.Select Tools to work.2. Contextualization of LMS tools to work.3. Leaning Objects.4. Structure of the LMS. 5. LMS ratings.6. Creating the map of knowledge for each LMS. 7. Comparison between the LMS modules modeled and 8. Conclusions.