Background and Objective: Orthosiphon sp., contains many active ingredients that are beneficial to health. In addition to prevention, they are also used in treatment. This study aims to evaluate the agronomic characteristics of 9 Orthosiphon sp., based on morphology and combine molecular biology methods to determine the genetic relationship based on the “ITS1-4” gene region. Materials and Methods: Nine seed samples/species Orthosiphon sp., grown in 9 provinces in South Vietnam were collected and planted for survey at the Can Tho experimental farm. The method of observing and describing the external morphology and microdissection of the eye cage is carried out. The DNA extraction was performed at the Molecular Biology Laboratory, Institute of Food and Biotechnology, Can Tho University. Results: There are differences in some parameters except leaf width and flower diameter. A simple pedigree chart can classify nine cat breeds into 3 groups: Group I includes An Giang (Râ1), Ca Mau (Râ2) and Can Tho (Râ3) breeds that are genetically close to each other and have only the same quantity, group II includes 2 varieties of Vinh Long (Râ8) and Dong Thap (Râ6), group III includes 4 identical samples in Kien Giang (Râ7), Hau Giang (Râ4), Soc Trang (Râ5) and Tien Giang (Râ9). Conclusion: With molecular biology techniques, 9 cat breeds have been identified, all belonging to the species Orthosiphon aristatus. However, to have more accurate and complete conclusions, it is necessary to study some specific gene sequences related to the morphology and substances contained in the plant.