The invention relates to an assistant used for producing a motor vehicle tail gas purifying converter, containing fatty acid, fatty acid glyceride, alcohol group or phenolic group polyethenoxy ether. The invention also relates to a production method of the assistant, which comprises the following steps: firstly, placing the fatty acid and the fatty acid glyceride into a reaction kettle to be heated to 60-80 DEG C; secondly, stirring the mixture for 2-3h at 60-80 DEG C until the mixture changes into transparency material; thirdly, adding the alcohol group or phenolic group polyethenoxy ether into the reaction kettle, stirring the mixture for 2-4h at 60-80 DEG C; fourthly, giving off the product of reaction before cooling, crushing solid after the product of reaction is naturally cooled so as to obtain the assistant. The invention shortens the milling time because assistant accounting for 8-20 percent of the weigh of the grout is added into the grout, can obtain the grout with uniform granularity, stable dispersion, no foam, and good levelability and easy loading. The invention has better comprehensive effect.