The invention discloses a fine grain copper-tin alloy. The alloy comprises following raw material components including, by mass percent, 10 to 16% of tin powder, 0.1 to 0.5% of titanium powder and thebalance copper powder. The sum of the mass percents if 100%, and the preparing method comprises following steps: firstly, according to the mass percent, the following components of 10 to 16% of tin powder, 0.1 to 0.5% of titanium powder and the balance copper powder are weighed; secondly, the components weighed in the first step are mixed, die pressing is carried out, sintering is carried out, and a sintering body is obtained through heat preservation; thirdly, the sintering body obtained in the second step is subject to surface treatment; fourthly, the sintering body treated in the third step is subject to induction smelting, the alloyed sintering body is heated to be in the molten state, heat preservation, stirring and rapid cooling are carried out, and the fine grain copper-tin alloy is obtained. Through the preparing method, the copper-tin alloy with the refine grains and uniform structure can be obtained.