Abstract: The rotating magnet ranging system (RMRS) is generally adopted in CBM connected horizontal wells to connect the cavity well with the horizontal well. And the intersection and connection between the horizontal well and the cave well is achieved by measuring the distance and azimuth between them. During the connecting operation, however, the connection accuracy drops for the horizontal displacement is too long and the accumulative error of measuring data is too large. To solve these problems, a set of technologies that can control the connected trajectory accurately were developed the basis of existing CBM connection technology by adopting the connection technology optimizing measures, the calculation technology of RMRS guided MWD measurement system, and the error evaluation, analysis and improvement technology of measuring data. The results of field application show that the success rate of the connection is increased to 100%, and it can be used in the construction of CBM connected wells.