A quizalofop-resistant Echinochloa crus-galli biotype (RR) was collected from Geqiushan Farm in Heilongjiang Province. Gramineae acetyl-CoA carboxylase (ACCase) in plastid is the target site of quizalofop. Two full-length cDNAs of the plastid ACCase from RR and sensitive Echinochloa crusgalli (SS) were cloned. Plastid ACCase cDNA from RR encodes a protein of 2316 amino acids with an estimated isoelectric point of 5.97 and a calculated molecular mass of 256 kD. The two sequences were compared with their homologs from other plants and the deduced proteins were analyzed to identify plastid ACCase. It was found that the amino acid at position 1781 (standardized to Alopecurus myosuroides) was Leu in RR, while Ile in SS and other cereal plastid ACCases. It was suspected that the change of Ile to Leu residue related to the resistance to quizalofop of RR.