A series of new green Cr-doped BiPO4 materials were synthesized by hydrothermal method and first used as solar heat-reflective pigments. XRD, FTIR, FE-SEM and HR-TEM analyses confirm that the phase structure was transformed from low-temperature monoclinic phase (LTMP) to hydrated hexagonal phase (HP), the particle size decreased and the morphology changed from irregular prism-shaped to rod-shaped, which all attributed to the incorporation of Cr3+ ions. Moreover, the valance of chromium ions was also confirmed by XPS. Color and ultraviolet-visible-near-infrared (UV-Vis-NIR) analysis indicate that different hues of green were obtained in these solid solutions and they possessed high NIR reflectance (> 83%) and solar reflectance (> 86%) in total NIR region. Meanwhile, the reason of decrease in NIR reflectance of doped samples was also analyzed, which mainly due to the decrease of free carrier concentration. TG-DTA and corrosion resistance tests prove that these pigments have excellent thermal and chemical stability. Compared with pure PMMA and the existing reports on pigmented PMMA, the NIR reflectance of PMMA pigmented with Cr-doped BiPO4 pigments have been greatly improved and have good coloring performance. The NIR solar reflectance of PMMA colored with Bi0.85Cr0.15PO4 in shortwave NIR region reaches up to 77.83%, an increase of nearly 52%. Heat aging test shows that Cr-doped BiPO4 pigments significantly improve the aging resistance of PMMA. In conclusion, these pigments have potential to become plastic colorants to increase the NIR reflectance and aging resistance of plastics.