Based TLJ250 continuous extrusion machine, experiments of continuous extrusion forming of copper bar was studied. The microstructure evolution of copper during continuous extrusion was analyzed by optical microscope. The results show that the grains of the clamping zone and the rigid mobile zone have a tendency to flatten. In the upsetting deformation zone, the grain is bent and deformed. In the adhesion zone, the large grain is broken under the action of shear force, which is obviously refined and shows the flow direction. In the right-angle bending zone, the grain has 90° lateral flow. In the extending extrusion zone, the grain is fully dynamic recrystallization, and the grain size is about 20μm.The average grain size of copper bar is 25 μm.