The invention discloses an additive and a method for improving coke quality. The additive for improving the coke quality is TiO2 powder with granularity of below 200-mesh and purity of above 95 percent. The method for improving the coke quality comprises the steps of: adding the additive accounting for 0.5-5 percent of the weight of coal in the coal, mixing with the coal and crushing for coking. The additive and the method provided by the invention not only can effectively reduce the reactivity of the coke, but also plays a role of protecting a furnace cylinder because the TiO2 can generate Ti(CN) high-melt matters adhered on the furnace cylinder in a blast-furnace process.