Abstract: For measuring the testing phase of glue applicator engagement during the electrical setting of blank unit in YB47 hard packer, a measuring device was designed according to the work principle and structure of the glue applicator. By finding out a reference benchmark, the device transferred the measurement of testing phase into measurement of the angle between test sensor and the benchmark. By means of infrared ray technology and electronic measuring element, the measurement of angle between two points, which were coaxial but not coplanar, was implemented and the angle value was converted into digital value for calculation and display. The results of practical application showed that the measuring device was simple and convenient in operation, the average time for phase measuring reduced from 14 to 4 minute, the reliability of setting results reached 100%. The device-measured phase could be used to determine whether the position of mechanical engagement point was correct, it ensured the normal running of glue applicator and effectively improved the efficiency of installation and setting.