The jassid, Amrasca devastans Distant (Homoptera: Cicadellidae) is an important pest on cotton in Ninh Thuan province, Vietnam. Cotton growers have sprayed to control the jassid weekly but jassid still causing serious damage on cotton. Insecticide resistance of jassid was studied at the chemical laboratory of Nha Ho Research Institute for Cotton and Agricultural Development. Main target of research was usage of insecticides in effectively controlling to jassid and preventing their resistance problem in Ninh Thuan province. The experiments were carried out with five replicates to estimate LC50, LC95 and resistant index (Ri) was made by division of LC95 with recommendation dose of insecticide manufacturer. The results showed that jassid resisted to three active ingredient of Acetamiprid, Imidacloprid and Fipronil with resistant index were 304.7, 183.8 and 76.6 respectively, compared to recommendation dose of insecticide manufacturer. Only active ingredient of indoxacarb was also sensitive against to jassid.