A variable-depth variable-pitch screw rod (1), a method for net-shape forging screw grooves (102) therefor, and a forging device therefor. The variable-depth variable-pitch screw (1) comprises screw threads (101) and the screw grooves (102), and the surfaces of the screw threads (101) and the screw grooves (102) are subjected to squeezing flow by means of a hydraulic forging machine (2) to form continuous metal fibers. The method for net-shape forging screw grooves (102) comprises: mounting an upper forging die (5) and a lower forging die (6) in a first step forging die in a guide die sleeve (4) of a forging and pressing device, and carrying out first-stage forging and pressing on a screw rod blank; mounting an upper forging die (5) and a lower forging die (6) in a second step forging die in a guide die sleeve (4), and carrying out second-stage forging and pressing on all the screw grooves (102) starting from the second step; and similarly, mounting an upper forging die (5) and a lower forging die (6) in an Xth step forging die in a guide die sleeve (4), and carrying out Xth stage forging and pressing on all the screw grooves (102) starting from the Xth step. The screw grooves (102) are formed by forging, so that the continuity of material fibers on the surface of a casting blank can be kept, and the structure is compact; moreover, no cutting machining is needed for the net-shape forging, and various performances of the screw rod can be well optimized.