The invention discloses a preparation method for 
telmisartan, and belongs to the technical field of pharmaceutical synthesis. The key points of the technical scheme lie in that in the preparation method for the 
telmisartan takes 
ionic liquid as a reaction medium, and 3-methyl-4-
nitryl-
benzoic acid as a 
raw material, 2-n-propyl-4-methyl-6- carboxyl 
benzimidazole is obtained successively through an 
esterification reaction, a reduction reaction, an 
acylation reaction, a nitratlon reaction, a reduction reaction and a cyclization reaction, then under the action of a polyphosphoric acid, the 2-n-propyl-4-methyl-6-carboxyl 
benzimidazole and N-methyl-o-phenlenediamine dihydrochloride are condensed to obtain 2-n-propyl-4-methyl-6-[1-methylbenzimidazole-2-yl] 
benzimidazole, 2-n-propyl-4-methyl-6-[1-methylbenzimidazole-2-yl] benzimidazole is condensed with 4,-
bromine biphenyl-2-
carboxylic acid methyl ester, and 
hydrolysis is carried out to obtain the 
telmisartan. According to the method, the 
ionic liquid is used for replacing 
methanol with larger 
toxicity in an original technology to be used as the reaction medium, raw materials are easy to obtain, the operation is simple and convenient, the yield is high, the purity of products is high, the residual quantity of an 
organic solvent is small, and the method is environmentally-friendly and is suitable for industrialized production.