The present invention provides a full-roadway full-process full-cross-section deformation monitoring device and a monitoring method thereof, which are applicable to the field of roadway surface deformation monitoring. A monitoring station is deployed utilizing an anchor rope, a supporting frame and a rotary laser measuring device are connected via a threaded sleeve at the tail end of the anchor rope, the rotary laser measuring device can rotate and drive a laser range finder to rotate, the data of a plurality of cross sections can be measured at the same time with one monitoring station, the data is processed by computer programming, so that the measurement data is converted into coordinates in a three-dimensional coordinate system, and thereby full-roadway full-process full-cross-section digital imaging is realized. The monitoring method attains high measuring accuracy, involves very low artificial error, supports intuitive observation of dynamic roadway deformation condition, can provide accurate warning for roof pressure condition, and provides a technical guarantee for safety of the downhole workers.