Abstract: Abstract: Experiment was conducted to evaluate the effects of lactic acid on development of digestive enzyme in piglets. 144 Duroc×Landrace×Yorkshire piglets were divided into 3 groups randomly， the control（basal diet），basal+3 g·kg-1 lactic acidifier and basal+6 g·kg-1 lactic acidifier， and the experiment lasted for 28 days. On the 7th， 14th and 28th day of experiment， 9 pigs were slaughtered， gastric and duodenal contents were taken out， duodenum and jejunum were taken for tissue slice， the intestinal mucosa was scraped for determination of enzyme activities. The pH and buffer value of feed were determined before animal trial. The pH of gastric and duodenum content， pepsin activity of gastric content， tripsin activity of duodenum content， disaccharidase activity of small intestinal， height of intestinal villus， and mucosa disaccharidase activity were determined on the 7th，14th and 28th day of trial. Results showed that supplement of lactic acid decreased pH of feed and gastric content， increased the pepsin activity of gastric content; increased the tripsin activity of duodenum content and disaccharidase activity of small intestinal; increased height of duodenum and jejunum villus; increased mucosa activity of disaccharidase. The results indicated addition of lactic acid improved the development of digestive enzyme， and promoted growth performance of pig via improvement of gastric and small intestinal development.

Key words: lactic acid, digestive enzyme, piglets, acidifier