The invention relates to a retractable constant force yielding anchor bolt for a dynamical pressure soft rock lane. The retractable constant force yielding anchor bolt consists of an anchor bolt body, a tray, a pull rod, a pre-tightening adjusting bolt, a main spring, a pin roll, a knife-shaped cam, an auxiliary spring, an anchor head framework, a roller, a roller rack and a nut, wherein the anchor bolt body is in threaded connection with the pull rod; the tray can move along the pull rod under the action of an external force; and in the moving process, a synthetic pre-tightening force to the tray caused by the main spring and the auxiliary spring is basically kept unchanged, namely the constant force is kept. When surrounding rocks of the dynamical pressure soft rock lane are deformed, the tray moves through belt load and yield so as to release the stress. After the surrounding rocks relive the pressure, the tray moves back for strengthening and realizes secondary reinforcing for the surrounding rocks. When the surrounding rocks are repeatedly deformed due to stress disturbance, the anchor bolt can form 'yielding-supporting-yielding circular support and flexible support for the surrounding rocks, and thus the damage on the lane is avoided. The retractable constant force yielding anchor bolt disclosed by the invention is ingenious in design and compact in structure; the tray has long moving stroke; and except an anchor bolt body, other parts of the retractable constant force yielding anchor bolt can be detached for recycling, so that the cost is saved.