The effect of potassium diformate on piglet performances were evaluated in this trail.108 Duroc×LW×BW piglets with weight 12.1 kg were distributed in a completely randomized design with 3 treatments,4 replicates,9 heads each replicates,to study the application method of potassium diformate.The results indicated that potassium diformate improved average daily gain and feed conversion rate,and the improvement is more in the first period,it also can prevent ablactation stress of the piglet on a certain extent.Potassium diformate has reduced the diarrhea rate and mortality of the piglets,and the supplement of 1% potassium diformate in the diet has not effect the palatability.Potassium diformate can also cooperate with antibiotics on prevent disease.