Abstract: Objective As cancer cachexia patients present low level of L-carnitine and abnormal energy metabolism, this study is to evaluate the impact of L-carnitine on energy metabolism of cancer cachexia patients. Methods We collected and analysed the results from the domestic and foreign published literature related to L-carnitine, cancer cachexia and energy metabolism in recent years. Results L-carnitine can ameliorate lipid metabolism disorders in cachexia patients, ameliorate anorexia by adjusting fatty acid metabolism in the hypothalamus; significantly decrease activities of proteasome related with protein metabolism, inhibit proteolysis,improve performance status and fatigue of patients; improve insulin resistance and increase insulin sensitivity. Conclusions The intervention of L-carnitine in cancer cachexia is worth paying attention to, but still need large sample research evidence to confirm,its underlying mechanisms also need further research.