Neurodegenerative diseases, such as Parkinson's and Alzheimer's disease, affect the elderly worldwide and will become more prevalent as the global population ages. Neuroinflammation is a common characteristic of neurodegenerative diseases. By regulating the phenotypes of microglia, it is possible to suppress neuroinflammation and, in turn, help prevent neurodegenerative diseases. This work reports a non-invasive photonic approach of regulating microglia from over-excited M1/ M2 to the resting M0 phenotype using a special NIR light emitted by the SrGa12O19:Cr3+ phosphor. The absorbance and internal and external quantum efficiencies of the optimal Sr(Ga0.99Cr0.01)12O19 phosphor synthesized at 1400 oC for 8 h using 1%H3BO3+1%AlF3 as flux were 53.9%, 99.2%, and 53.5%; and the output power and energy-conversion efficiency of the LED device packaged using the optimal SrGa12O19:Cr3+ phosphor driven at 20 mA reach unprecedentedly 19.69 mW and 37.58%, respectively. The broadband emission of the NIR LED device covers the absorption peaks of cytochrome c oxidase well; and the NIR light can efficiently promote the proliferation of microglia, produce ATP (Adenosine-triphosphate triphosphate), reverse overexcitation, alleviate and inhibit inflammation, and improve cells survival rate and activity, showing great promising for photomedicine application.