Abstract: For understanding the borax background level in yuba, relationship between raw material borax background and borax content of yuba were investigated. Based on the background survey of borax, online research was performanced to research the transportation of borax during processing. The result showed that content range of yuba sample were from 20.1 to 171mg/kg. Borax migration research result showed borax migrated to the water partly in the process of bubble, and borax content decreased. The migration of almost 70% of borax soya-bean milk during refining occurred. During extracting, distribution coefficient of borax between soya-bean milk and wet yuba was more than 1, that was to say, borax got concentrated. Finally, borax content in yuba was lower than that in raw materials.