Abstract: The systematic position of Polygonum perfoliatum has been in dispute.Phylogenetic analyses were conducted on sequences of chloroplast trnL-F sequences for species of Polygonum perfoliatum and allies.Rheum nobile was designed as outgroup.The analyses were performed using parsimony reconstruction methods.Some conclusions could be achieved as follows.(1)Polygonum perfoliatum and P.senticosum were sister group with a bootstrap value of 99%.Therefore,Polygonum perfoliatum should be ascribed to Polygonum Sect.Echinocaulon;it was unnecessary to accord genus rank or section rank.(2)Sect.Echinocaulon and Sect.Persicaria clustered with Sect.Cephalophilon with a bootstrap value of 100%,indicating their close affinity.