Abstract: The fish-bone, fish-skin and fish-head of catfish by-products were studied, and the shearing technology was applied to the ultra-fine grinding and pulping. The cumulative sieving percentage of the controlled cutting grinder under different numbers of static blades and grinding cycles was measured through sieves, stability was observed, and the viscosity was measured. The result showed that, with 222 static blades and 3 grinding cycles, the cumulative sieving percentages of pulping made of the fish-bone, fish-skin and fish-head through a 150-mesh sieve reached 90.00%, 82.50%, 88.75%, respectively. The fish-skin was the most difficult one to grind and its pulping had the highest viscosity, pulping from the fish-bone had the highest stability, the increasing of grinding cycles would result in the agglomeration of pulping, the number of grinders' static blades imposed a bigger impact on the pulping's particle size, stability and viscosity compare with that of the number of grinding cycles. The experimental results of applying shearing technology to the ultra-fine pulping of catfish by-products met the needs of practical application.