Objective To study major influential factors of the micturition alert device dedicated to neurogenic bladders for the product design and cl inical appl ication of the device. Methods One ferrite permanent magnet with thickness and diameter of 3 mm and 10 mm, respectively, and three NdFeB permanent magnets with the thickness of 3 mm and diameter of 10, 15 and 20 mm, respectively, were used. The effects of thickness of the abdominal wall as well as the position and type of permanent magnets on the micturition alert device dedicated to neurogenic bladders were measured in vitro simulated test, when the abdominal wall was set to 2, 3, 4, 5, 6, 7, 8 and 9 cm, respectively, and the position of permanent magnets was 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12 cm, respectively. The effect of the geomagnetic field on the device was measured under the condition that the thickness of the simulated abdominal wall was set to 2, 3, 4 and 5 cm, respectively,and the position of permanent magnets was 2, 3, 4, 5, 6, 7, 8, 9 and 10 cm, respectively. Results The value showed inthe warning unit was positively correlated with the position of the ferrite permanent magnet only when the thickness ofthe simulated abdominal wall was 2 cm (r=0.632, P lt; 0.05). The correlation between the value of the warning unit andthe position of NdFeB permanent magnets was significant (r gt; 0.622, P lt; 0.05), which was intensified with the increasingdiameter of NdFeB permanent magnets, but weakened with the increasing thickness of the simulated abdominal wall. The effect of the geomagnetic field was correlated with the exposition of the body, the position of the permanent magnet and the thickness of the abdominal wall. Conclusion The major influential factors of the micturition alert device dedicated to neurogenic bladder include the magnetism and location of the permanent magnet, the thickness of the abdominal wall and the geomagnetic field. These factors are correlated with and affect each other. Reasonable allocation of these factors may optimize the device.