Objective To develop an instrument that detects the endurance of an animal hanging on a bar during medical and pharmaceutical scientific experiments. Methods One pair of opto sensors were used for signal conversion. A solenoid valve device was used for water level. A 51-Series microcontroller was used to control the experimental setup and record the results. Results We have developed a microcontroller-based experimental instrument that can automatically detects the endurance of an animal hanging on a bar during medical and pharmaceutical scientific experiments. Our experimental results with 28 mice indicated that the applicability of the instrument is good. Conclusion The instrument provides an innovative tool for detecting the endurance of an animal.