The invention discloses an abrasive agent for manufacturing a semiconductor device, wherein the abrasive agent is prepared from the following materials by the mass percentage: 0.01-20% of amino functionalized silica particles, 0.01-5.0% of an additive, and the balance water, wherein the amino functionalized silica particles are prepared through reaction of silica particles and amino silane. The invention further provides a preparation method of the abrasive agent. The amino functionalized silica particles are used as an abrasive material for a chemical mechanical abrasive agent, selective grinding of the abrasive agent on silica and silicon nitride is improved, and scratching defects on a chip surface in a CMP process are significantly reduced, so that a good grinding effect is achieved.