Abstract: Using the total RNA from the leaves of Malus crabapple‘Royalty’as the template，the full cDNA of ANS（anthocyanidin synthase）gene（1 350 bp）was cloned by reverse transcription polymerase chain reaction（RT-PCR）and rapid-amplification of cDNA ends（RACE）. The gene was named as McANS，containing an open reading frame（1 074 bp）and encoding a protein of 357 amino acids. Corresponding DNA sequence is 1 268 bp，containing one intron，and all the cleave sites obey with the GT-AG rule. The expression of McANS and the content of anthocyanins and flavonoids was determined by real-time quantitative PCR and spectrophotometer respectively in the mature and young leaves of M.‘Flame’（green young and mature leaf），M.‘Radiant’（red young leaf and green mature leaf），M.‘Royalty’（purple young and mature leaf）. The results showed that McANS was expressed in both mature leaves and young leaves of the above three cultivars，and the expression level of McANS in young leaves is higher than in mature leaves，23.82-fold difference in M. ‘Radiant’. The trends of anthocyanins content had significant consistency with that of the relative expression of McANS gene. But flavonoids content had not relevance with relative expression of McANS gene. It’s description that McANS have very close relationship with the metabolism of anthocyanins and color of leaf.

Key words: Malus, ornamental crabapples, ANS, anthocyanin, flavonoid, real-time quantitative PCR