Mycobacterium Tuberculosis (MTB) is the pathogen that could induce severe contagious disease. The cell wall of MTB is complexed and composed of complicated components, such as lipids. The envelope of MTB is the high content of lipid, constituting up to 60% of the dry weight of mycobacteria. It has been demonstrated that the prominent role is played by mycobacterial lipids in pathogenesis, notably in tuberculosis. The most lipids are phthiocerol dimycocerosate (PDIM), which is an important cell wall lipid of pathogenic mycobacterium and it has been intensively studied since being shown to promote MTB virulence. Recent studies have suggested that PDIM play a role in cell wall permeability, modulating the early immune responses of murine macrophages, participating in both the receptor-dependent phagocytosis of Mtb and the prevention of phagosomal acidification. However, its cellular and molecular mechanisms of action still remain unknown. Thus, research on the pathogenicity of PDIM not only is helpful to understand the interaction between bacterium and host cell, but also brings a new hope and a breakthrough for the TB treatment.