Abstract: In response to the problem that the oil level abnormal signal is probably mistakenly sent due to the damage of the reed switch after a long-term operation of the reed switch type oil level gauge, as well as the difficulty in purchasing the reed switch and the complexity of the replacement process. The article develops a universal alarm device that can replace the transmission shaft module with a reed switch as the alarm unit. It has the characteristics of simple installation, universal size, low cost, and reliable operation, which can significantly improve the efficiency of oil level gauge troubleshooting, reduce the cost of oil level gauge replacement and the dependence on original spare parts, and improve the business efficiency of the enterprise.