Objective    To use the ultrasound to detect the diaphragm thickening rate, the abdominal muscle thickening rate, and diaphragmatic activity. Constipation scoring system is used to evaluate the curative effect, so as to make clear how does the respiratory electric stimulation training play a part in the functional improvement of diaphragm and abdominal muscle.  Methods  46 patients with functional constipation were included in the study for two weeks of treatment. According to the random number, the method is divided into the treatment A group, the treatment B group and the control group. The treatment A group with 15 cases given Lactulose 2 times /day, also underwent pelvic floor muscle biofeedback therapy and respiratory stimulation training 20 minutes each day，3 times/week. In the treatment group B with 16 cases given Lactulose 2 times /day were treated with biofeedback therapy of pelvic floor muscle 20 minutes each day. In the control group, 15 cases were treated with Lactulose 2 times /day. Both at the beginning and end of the treatment, all patients were evaluated by the constipation scoring system, and ultrasonography was used for detection of the diaphragm thickening rate, the abdominal muscle thickening rate, and diaphragmatic activity.　Results　After 2 weeks, in the three groups, the scoring of constipation decreased before treatment (P<0.05). And A group had a score lower than the treatment B group and the control group (P<0.05).The diaphragm thickening rate, the abdominal muscle thickening rate, and the diaphragmatic activity of patients from the treatment of A group were improved than prior to treatment (P<0.05), and there was a statistical difference compared with treatment B group and control group(P<0.05).    Conclusion　Respiratory electric stimulation training can effectively improve the contraction strength of the diaphragm and the abdominal muscle, which can enhance the treatment of pelvic floor muscle biofeedback therapy and improve the effect to functional constipation.