The unattended ore grading radioactivity measurement system is an important part of the digital uranium mine. However, with the promotion of the digitization of mines, the radioactivity measurement system for the truck checkpoint used to measure the grade of ore for hydrometallurgical process still maintains the backward processing method of offline measurement and manual recording. To improve the situation, an unattended ore grading measurement system using gamma detectors is developed. Through unattended identification, weighting and radioactivity measurement, the values of the grade of ore and the uranium content are calculated and uploaded automatically. The system has been put into practical use at a uranium mine in southern China in September 2021. Through the field use, the system can realize automatic measurement, reduce labor costs, and establish a production database, which lays the foundation for further application in the construction of digital mines on a large scale.