A practical chemical synthesis of L-carnitine (1) has been accomplished from (R)-3-chloro-l,2-propanediol ((R)-4), which is a main by-product originated from (R,R)-Salen Co(Ⅲ) catalyzed hydrolytic kinetic resolution (HKR) of (±)-epichlorohydrin. (R)-4 was utilized as a chiral starting material to prepare the key intermediate cyclic sulfite ((R)-5). The new synthetic approach demonstrated an efficient utilization of organic by-product for the asymmetric synthesis of bioactive compounds.