Objective To investigate efficacy and safety of Fiberform and Lactulose for the treatment of functional constipation in children. Methods This retrospective study enrolled 107 children aging from 0 to 4 years old. All children including the ones in control group received standard treatment including Lactulose. Patients in observation group received additional Fiberform. Primary efficacy was evaluated by stool difficulty and stool frequency score. Secondary endpoint of this study was to record adverse reactions. Results The score of stool difficulty and stool frequency was comparable in the two groups before any treatments (P > 0.05). Score of stool difficulty and stool frequency were improved significantly in both group after standard treatments compared with those prior any treatments (P < 0.05). Score of stool difficulty and stool frequency were significantly decreased after 2 and 4 weeks of treatment in observation group when compared with those in control group (P < 0.05). The incidence of adverse events was similar in both groups (P > 0.05). Conclusions Fiberform and Lactulose exert superior efficacy to the treatment of functional constipation in children without obvious or severe side effects.