The invention relates to a friction welding axial deformation precision control process. The friction welding axial deformation precision control process includes a rotating workpiece 1, a moving workpiece 2, a spindle system 3.1, a rotating member fixture 3.2, a moving sliding table system 4.1, a moving member fixture 4.2, a welding loading mechanism 5, a lathe bed 10.1, a guide rail moving pair10.2, a power-driven system 11, a hydraulic system and connecting line 12, a torque sensor 6, a displacement sensor 7, a pressure sensor 8 and a friction welding control system 9. Based on friction torque jump/axial welding pressure jump determination conditions, the problem of automatic measurement of workpiece axial dimensional precision in the welding preparation process and the problem of accurate compensation of the spacing generated by the rotating workpiece and the moving workpiece in the welding process are solved, the accurate control over the axial shortening amount of the friction welding is realized, and the axial dimensional precision of an axial friction welding workpiece and the quality of friction welding products are improved.