Abstract: The physiochemical effect of surfactant on the machining of pure copper was clarified by the study on microstructure characterization on the cross-sectioned microgroove. An obvious decreased cutting force and thrust force were obtained by adding surfactant. It could be found that the surface roughness of microgroove with physiochemical effect was 12 nm, and that without physiochemical effect was 17 nm. The average grain size of the medium-affected sample was 67.9 μm within the microgroove zone, and that of the medium-free sample was 48.3 μm within the microgroove zone. Moreover, the grain size of medium-free microgroove near the microgroove surface was larger than that far away from the microgroove surface. Additionally, observed by electron backscattering diffraction microscopy, the grain orientations of medium-affected cross-sectioned surface presented anisotropy, while that of medium-free cross-sectioned surface were 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 in the microcutting process, which can provide enough driving energy for recrystallization.