The experiment was conducted to study the effects of the addition of encapsulated and nonencapsulated compound acidifiers in a diet based on maize-soyabean meal-extruded soyabean on gastrointestinal pH, growth performance, villus height and crypt depth of jejunum, intestinal digestive enzymes activities, microbial population and intestinal mucosal secretory immunoglobulin A in weaning piglets. Sixty-four 28-day-old, crossbred piglets (Landrace×Large White), weighing an average of 7.00 ± 0.10 kg, were randomly assigned to four treatments with four replicates and four piglets (2 male and 2 female) per pen, according to single-factor design principle. The feeding trial lasted 35 days. The results showed that encapsulated compound acidifiers significantly reduced the gastrointestinal pH (P<0.01), and improved the average daily gain and the feed conversion ratio (P<0.05), but they had no significant effect on the average daily feed intake. In addition, encapsulated compound acidifiers significantly increased the ratio between the villus height and crypt depth of jejunum (P<0.01), and stimulated the sucrase activity and lactase activity (P<0.05) as well; during the later weaning period, encapsulated compound acidifiers significantly increased the counts of Lactobacillus and decreased the counts of Escherichia coli in the caecum and the colon (P<0.01); it was also noted that there was an insignificant tendency of lower secretion of intestinal mucosal secretory IgA (P>0.05). These results indicate that the encapsulated compound acidifiers improve the intestinal morphology and function by reducing the gastrointestinal pH, so as to enhance the intestinal adaptation and immunity, and consequently improve the growth performance of weaning piglets.