Objective Use high-frequency ultrasound to determine the frequency of visualization and image feature of the appendix in children with acute appendicitis (acute appendicitis, AA) and with acute infectious enteritis (acute infectious enteritis, AIE). Methods The ultrasonic features of 120 children with AA, 160 children with AIE, and 120 randomly selected asymptomatic children were analyzed retrospectively. And their visualization rate, outer appendiceal diameter, presence or absence of inflamed periphery appendiceal mesenterium, and location of the appendix were recorded. Results The visualization rates of the appendix were 96.7%, 80.6%, and 68.3% for AA groups, AIE groups, and the control, respectively(P<0.05). The outer appendiceal diameters for the 3 groups were (8.5±2.2)mm, (4.3±0.8)mm, and (3.5±0.7)mm. Difference among the 3 groups was statistically significant also. Periphery appendiceal inflamed mesenterium was detected in all AA cases, but in none of the AIE cases. Conclusion High ultrasound imaging sensitivity of puerile acute appendicitis provided relatively accurate comprehensive imaging basis for clinical early diagnosis and early treatment.