Objective Car paint frequently presents in the scene of hit-and-run accident. The inorganic substances in the paint are important to characterize the paint. The integrity of information about the paint is essential for ascertainment of the accident car. In order to accurately identify the inorganic substances in car paint, this paper tries to apply micro X-ray diffraction (micro-XRD) into analyzing the inorganic constituents of the filler in car paint. Methods The analysis of three car paint samples owning same color was conducted with the micro-XRD to verify the inorganic composition. The results were compared with those obtained by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS). Results Inorganic composition, achieved by the micro-XRD from three samples, was consistent with the one by FT-IR and SEM/EDS, yet showing more accurate phase information. Conclusion Micro-XRD is a very attractive technique for paint analysis, able to discriminate the different inorganic substances in diverse paints. The method has advantages of sampling within micro area, in situ detection of minimal specimen quantity and non-destruction for the analyzed object, reaching the same or even better accuracy as that from large quantity of tested materials by the ordinary approach of X-ray diffraction. The micro-XRD, in combination with other measurements, can make different paints distinguished. Therefore, micro-XRD is very likely to hold a wide application prospect for forensic identification.