The clinical urination assist measures are usually taken to overcome the neurogenic bladder difficult to cure, but easily cause patients bladder stones, urinary system infection and other complications. To solve the problem of the urination assist of neurogenic bladder, a bladder power pump (BPP) driven by external electromagnet was proposed in this study according to the structure and micturition mechanism of human urinary bladder. The mathematic models of the BPP were established based on the theories of electromagnetics and fluid dynamics. A simulated experiment system with a bladder physical model for simulating human urinary system was designed according to the similarity criterion of fluid dynamincs. The micturition performance of the BPP was investigated by simulation and experiment. The results showed that the intravesical pressure and urine flow rate of the bladder physical model can be controlled by adjusting electromagnet exciting current. The micturition performance of the BPP is basically accordant with that of human urinary bladder detrusor. The established mathematic models are simple and practicable, which can provide the theoretical guidance for the performance analysis and structural optimization design of the BPP.