A polishing slurry for silicon, a method of polishing polysilicon, and a method of manufacturing a thin film transistor substrate, the slurry including a polishing particle; a dispersing agent including an anionic polymer, a hydroxyl acid, or an amino acid; a stabilizing agent including an organic acid, the organic acid including a carboxyl group; a hydrophilic agent including a hydrophilic group and a hydrophobic group, and water, wherein the polishing particle is included in the polishing slurry in an amount of about 0.1% by weight to about 10% by weight, based on a total weight of the slurry, a weight ratio of the polishing particle and the dispersing agent is about 1:0.01 to about 1:0.2, a weight ratio of the polishing particle and the stabilizing agent is about 1:0.001 to about 1:0.1, and a weight ratio of the polishing particle and the hydrophilic agent is about 1:0.01 to about 1:3.