Harmane, a compound derived from Peganum harmala L., was discovered as a lipid accumulation inhibitor with our triglyceride (TG) assay. To investigate the molecular mechanism underlying the role of harmane in the prevention of lipid accumulation, a number of biological experiments have been designed to determine if harmane reduces lipid accumulation by suppressing adipogenesis, lipogenesis, and regulating a specific signal transduction pathway. Our experimental data show that harmane inhibits TG accumulation though down-regulating the expression of adipogenic and lipogenic factors, up-regulating adipocyte browning markers and activating the SIRT1-LKB1-AMPK pathway. Therefore, harmane ameliorates obesity though inhibiting lipid accumulation and inducing adipocyte browning.