Abstract: Objective　To investigate the characteristics of maturation of gastrointestinal motility and secretion function in different gestational age preterm infants within 28 days after preterm infant birth. Methods　The preterm infants were divided into young gestational age (GA) group (<32 weeks, n=15) and older GA group (32 - 37 weeks, n=15) by GA, and 15 term infants were selected as control group. On the 7th, 14th, 21th and 28th day after birth of preterm infants, and the 7th day after birth of term infants, gastric emptying rate (GER) and gastric motility index (MI) were detected by ultrasound; pH and pepsinogen (PG) levels of gastric juice extracted by stomach tube were tested. Results In both GA groups, GER and MI gradually increased with age. GER on the 21th and 28th day and MI on the 14th to 28th day of young GA group were lower than that of older GA group (P<0.05). And the time of GER and MI levels up to term infants in young GA group was later than that of older GA group. The pH in two GA groups both increased at first and then decreased (P<0.05). Compared to the older GA group, the pH was higher at 7th, 14th and 21th day in young GA group, and the difference was statistically significant (P<0.05). Only the gastric pH on the 14th and 21st day of young GA group was higher than that of term infants (P<0.05). PG level of young GA group in each point was lower than that of older GA group (P<0.05). Compared to term infants, the PG level of both groups of preterm infants was lower(P<0.05), and the PG level only on the 28th day of older GA group showed no difference with that of term group (P>0.05). Conclusions The gastrointestinal motility and gastric secretion of young GA group was lower than that of older GA group and term group. More cautious feeding strategies should be adopted for preterm infants with younger GA. GER and MI can be used as objective indicators to evaluate gastrointestinal motility of preterm infants.