The work aims to establish a standardized evaluation analysis process for analyzing surface microstructure of diesel engine nozzle holes. Section of the nozzle holes was obtained by wire-electrode cutting and grinding. Surface microstructure of three product-level nozzle holes was tested with white light interferometry and scanning electron microscope. The microstructure characteristics of the nozzle holes were analyzed and evaluated based upon fractal theory. Finally, 3D reconstruction of the microstructure was realized in the method of Monte Carlo based upon the key parameters-amplitude root-mean-square and correlation length. Along the axis of orifice with evaluation length of 0.6 mm, hole surface roughness of sample A, B and C was 0.33, 0.25 and 0.11 ?m, respectively. The fractal dimension of hole surface was 1.54, 1.61 and 1.82, respectively based on power spectrum. Surface processing quality of sample C is the best among three injection nozzles being processed in different tech-nologies, which is consistent with the testing results of SEM. The surface processing quality of diesel nozzle hole can be evaluated reasonably by combining Ra value and fractal method. Meanwhile, the 3D reconstruction model of injection nozzle based upon characteristic parameters provides effective solutions for surface microstructure visualization and CFD calculation model.