We are interested in designing a Project-Based Learning Management System (PBLMS) for high school students. In this paper, we focus on the study of ergonomics of existing PBLMSs. We first analyze four different PBLMSs regarding three points: aims, functionalities and indicators. We particularly focus on the indicators and analyze their attributes: purpose(s), concept(s), data construction and visualization. Based on this analysis we discuss the utility, the usability and the acceptability of the studied systems according to their functionalities, the types of visualization and the users. We finally conclude with some directions of our future research work.