To study the effect of shear thickening polishing fluid on the cutting edge of milling cutter, a four-edge high speed steel flat end milling cutter was taken as the research object, and the high speed steel cutter was trimmed.The cutting edge radius of the milling cutter was measured and the cutting edge morphology of the milling cutter was observed.The experimental results showed that the cutting edge radius decreased after trimming, but the cutting edge radius decreased to different degrees due to the different initial states.The maximum change was 7.5 μm, and the minimum change was 0.4 μm.In the trimming experiment, only the cutting edge of the milling cutter was trimmed.The front and back face of the milling cutter did not change obviously.The grinding marks were not removed.Abrasive particle size had a certain influence on the trimming effect.After trimming, the average cutting radius of a, b and c three silicon carbide STF experimental groups decreased by 4.6 μm, 3.6 μm and 1.9 μm, respectively.The larger the grinding particle size was, the more obvious the change of milling cutter edge radius was.