NOVELTY - A 3-chloro-2-methyl-N-(5,8-dimethoxy-(1,2,4)triazolo (1,5-c)pyrimidin-2-yl)benzenesulfonamide is new.    USE - Triazolopyrimidine sulfonamide compound is used as herbicide in rice field (claimed).    ADVANTAGE - The triazolopyrimidine sulfonamide compound is economically prepared.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of 3-chloro-2-methyl-N-(5,8-dimethoxy-(1,2,4)triazolo (1,5-c)pyrimidin-2-yl)benzenesulfonamide, which involves adding glacial acetic acid and concentrated hydrochloric acid to 2-methyl-3-chloro aniline, stirring at room temperature, obtaining white precipitate, providing at -10 degrees C to -5 degrees C for 2-5 mL/minutes, adding ??dropwise aqueous sodium nitrite solution with concentration of 0.5-0.7 g/mL, obtaining orange-yellow solution, maintaining at -10 degrees C to -5 degrees C for 40-50 minutes, obtaining diazonium salt, adding sulfur dioxide gas into glacial acetic acid at stirring speed of 150-250 rpm under gas flow rate of 5-10 cm3/minute for 25-35 minutes, obtaining yellow-green solution, adding copper chloride at stirring speed of 150-250 rpm, obtaining blue solution, continuing into sulfur dioxide gas under gas flow rate of 5-10 cm3/minute for 15-25 minutes, cooling at 0-5 degrees C at stirring speed of 150-250 rpm, adding dropwise diazonium salt under acceleration of 2-5 mL/minute, controlling the reaction temperature at 30 degrees C, continuing the reaction at room temperature at speed of 150-250 rpm for 25-35 minutes, obtaining 2-methyl-3-chlorobenzenesulfonyl chloride crude, pouring 2-methyl-3-chlorophenyl crude and sulfonyl chloride into ice-water, stirring for mixing and then filtering, obtaining pale yellow solid, dissolving light yellow solid in dichloromethane, performing stratification, removing aqueous layer, drying organic layer using anhydrous sodium sulfate, performing vacuum distillation under pressure of 0.08-0.1 MPa, removing the solvent at 25 degrees C, obtaining 2-methyl-3-chlorobenzenesulfonyl chloride, adding 2-amino-5,8-dimethoxy(1,2,4)triazolo(1,5-c) pyrimidine in acetonitrile, adding dimethyl sulfoxide, reacting 2-methyl-3-chlorobenzenesulfonyl chloride and pyridine at 45-55 degrees C for 12-16 hours, obtaining 3-chloro-2-methyl-N-(5,8-dimethoxy-(1,2,4)triazolo(1,5-c)pyrimidin-2-yl)benzenesulfonamide crude, adding 3-chloro-2-methyl-N-(5,8-dimethoxy-(1,2,4)triazolo (1,5-c)pyrimidin-2-yl)-benzenesulfonamide crude in the 10-20 %mass aqueous sulfuric acid, stirring at speed of 150-250 rpm to room temperature for 50-70 minutes, filtering, obtaining gray solid, washing with deionized water and drying at 50-70 degrees C. The volume ratio of glacial acetic acid and concentrated hydrochloric acid is 0.2-0.4:1. The volume and mass ratio of 2-methyl-3-chloroaniline and concentrated hydrochloric acid is 0.3-0.5 g:1 mL. The volume ratio of concentrated hydrochloric acid and aqueous sodium nitrite solution with concentration of 0.5-0.7 g/mL is 0.3-0.5:1. The volume ratio of diazonium salt and glacial acetic acid and is 0.7-1:1. The volume ratio of diazonium salt and copper chloride is 0.03-0.05 g:1 mL. The volume ratio of ice and 2-methyl-3-chlorobenzenesulfonyl chloride crude is 5-7:1. The volume ratio of 2-amino-5,8-dimethoxy(1,2,4)triazolo(1,5-c)pyrimidine and acetonitrile is 1 g:9-11 mL. The mass ratio of 2-amino-5,8-dimethoxy(1,2,4)triazolo(1,5-c)pyrimidine and dimethyl sulfoxide is 1:0.1-0.2. The mass ratio of 2-amino-5,8-dimethoxy(1,2,4)triazolo(1,5-c)pyrimidine and 2-methyl-3-chlorobenzenesulfonyl chloride 1:1.2-1.4. The mass ratio of 2-amino-5,8-dimethoxy(1,2,4)triazolo(1,5-c) pyrimidine and pyridine is 1:2.4-2.6. The volume ratio of aqueous sulfuric acid and 3-chloro-2-methyl-N-(5,8-dimethoxy-(1,2,4)triazolo(1,5-c)pyrimidin-2-yl)benzenesulfonamide crude is 2-3:1.