Carnitine is a nonessential amino acid participating in the transport of long-chain fatty acids to mitochondrial matrix for β-oxidation and subsequent energy production. The main sources of carnitine are dietary intake and endogenous synthesis in liver and kidney. Carnitine deficiency occurs in dialysis patients due to reduced dietary intake, lack of endogenous synthesis in kidney and dialysis loss. The symptoms of carnitine deficiency include erythropoiesis stimulating agents (ESAs) resistant anemia, muscle weakness, muscle spasm, hypotension and dyslipidemia. Peritoneal dialysis (PD) as an important renal replacement therapy has the advantages of protecting residual renal function, stabilizing hemodynamics, no need for vascular puncture, and less impact on daily life, and is accepted by most end-stage renal disease (ESRD) patients. This article reviews the relevant studies of L-carnitine in PD patients, and summarizes the characteristics of carnitine, the causes and prevalence of carnitine deficiency in PD patients, and the efficacy of L-carnitine supplementation in PD patients.