The CR-39 detector is used in this work to present an exceptional technique for alpha-particle spectrometry. This new approach is based on determining the mean grey level and visibility of the alpha particle track etch-pit. The latter is used to discriminate alpha particles of different energies that produce the same track diameter at the same etching time. CR-39 detectors had been irradiated by alpha particles with energies 1, 2, 3, 4, and 5 MeV thereafter are chemically etched in 6.25 M NaOH at 70 °C. At various etching periods, the diameter, the mean grey level, and the visibility of the alpha particle track etch-pit were measured. The findings reveal that for a given alpha particle, the mean grey level rises with the increase of the etching time. Conversely, both the visibility and contrast of alpha particle tracks are deteriorating. The alpha particle track etch-pit of equal diameters results from an alpha particle of different energies having different mean grey levels and visibility. In addition, it is confirmed that the mean grey level and visibility of the alpha particle etch-pit are shown to be correlated with the alpha particle energy at a particular etching time. Finally, the proposed approach is intended to overcome the non-monotonical relationship of diameter to the energy of alpha particle track etch-pit. So, our findings have the potential to broaden the application of CR-39 as an alpha particle spectrometer.