Abstract: To ensure the accuracy and reliability of the tension sensor of the mask machine through traceability, a calibration device was designed for online measurement of the tension system without disassembling the sensor and other parts of the mask machine. Using the method of force value step loading, a standard force value is applied along the force axis of the force sensor to measure the tension sensor and complete the online calibration of the metrological characteristics of the tension sensor. The calibration device can be used to accurately measure and calibrate the tension sensor of the mask machine under different working conditions to ensure that the manufactured masks meet the requirements of relevant standards. The calibration device is designed using Solidworks software, and the performance of the device meets the design requirements after metrology testing. The calibration results of the mask machine tension sensor meet the range specified in the standard.