The present invention discloses a method for improving the accuracy of activity detection of the total cellulase in a feed. According to the method, on the basis of a conventional cellulase detection method, a feed is subjected to pretreatment such as metal removing and sugar removing; and the concrete steps comprise: pouring a crushed feed and a metal settling agent into a buffer liquid, extracting, filtering, adding a sugar removing agent to the filtrate, carrying out a reaction, filtering after the reaction to obtain an enzyme liquid, crushing filtration paper into cotton-like paper, adding the cotton-like filtration paper to the enzyme liquid, carrying out an enzymolysis reaction at a temperature of 37 DEG C, adding a DNS reagent after the reaction, boiling to inactivate the enzyme, filtering, taking the filtrate, measuring the absorbance at 540 nm, comparing to a standard curve to obtain a monosaccharide concentration, and calculating the activity of the enzyme according to a specific formula. Compared to the existing detection methods, the method of the present invention has advantages of greatly improved accuracy, less sample consumption, good repeatability and simple convenient operation, and can effectively improve the inaccuracy of the quantitative detection of the cellulase in the feed.