Physiochemical effect on the machining of pure copper is studied via microstructure characterization on the cross-sectioned microgroove. An obvious decreased cutting force and thrust force were obtained with the application of surfactant. The surface roughness of microgroove with physiochemical effect is 12 nm, and that without physiochemical effect is 17 nm. The average grain size of the medium-affected sample is 67.9 µm within the microgroove zone, and that of the medium-free sample is 48.3 µm within the microgroove zone, moreover, the grain size of medium-free microgroove near the microgroove surface is larger than that far away from the microgroove surface. Additionally, the grain orientations of medium-affected cross-sectioned surface present anisotropy, while that of medium-free cross-sectioned surface are towards {101} direction. Based on the calculation and analysis of geometrically necessary dislocation, it can be inferred that the induced stress and temperature in the sample with physiochemical effect are higher than that without physiochemical effect, which can provide enough driving energy for recrystallization.