NOVELTY - Preparing 41% glyphosate isopropyl amine salt aqueous agent comprises: carrying out alkaline hydrolysis of iminodiacetonitrile, acidifying the reaction, carry out condensation reaction, crystallizing, and filtering to obtain intermediate phosphonomethyl iminodiacetic acid (PMIDA); oxidizing PMIDA to obtain glyphosate and activated carbon mixture, crystallizing, filtering to obtain glyphosate and active carbon solid mixture; adding water and isopropylamine to obtain 46% glyphosate isopropylamine salt mother drug, glyphosate mother liquor and activated carbon mixture, filtering, and diluting.    USE - The method is useful for preparing 41% glyphosate isopropyl amine salt aqueous agent (claimed).    ADVANTAGE - The method greatly simplifies the glyphosate isopropylamine production process by eliminating amination, acidification, crystallization, centrifugation and drying processes, can improve the product yield by 8%, reduces the production cost and raw material consumption, consumes less energy and reduces environment pollution.    DETAILED DESCRIPTION - Preparing 41% glyphosate isopropyl amine salt aqueous agent comprises: (i) carrying out alkaline hydrolysis of iminodiacetonitrile by adding aqueous sodium hydroxide, acidifying the reaction by adding phosphorus trichloride and hydrochloric acid, carry out condensation reaction by adding formaldehyde, and crystallizing by adding aqueous sodium hydroxide, and filtering by adding water to obtain intermediate phosphonomethyl iminodiacetic acid (PMIDA), (ii) oxidizing intermediate PMIDA in the presence of catalyst and activated carbon to obtain glyphosate and activated carbon mixture, cooling and crystallizing the glyphosate and activated carbon mixture, filtering and separating to obtain the glyphosate and active carbon solid mixture, (iii) adding water and isopropylamine into the glyphosate and active carbon solid mixture to obtain 46% glyphosate isopropylamine salt mother drug, glyphosate mother liquor and activated carbon mixture, filtering the mixture to obtain 46% glyphosate isopropylamine salt mother drug, glyphosate mother liquor and activated carbon, and formulating 46% glyphosate isopropylamine salt mother drug into 41% aqueous glyphosate isopropylamine salt, where the obtained glyphosate mother liquid and active carbon filtrate is washed, and filtering to obtain glyphosate mother liquor, which is returned to repeatedly prepare isopropylamine, and activated carbon is used as a catalyst in step (ii).