Phosphors-converted near-infrared LED (pc-NIR LED) is finding applications in various fields including food quality analysis, night vision, biomedical imaging, and biomedicine. The design and development of broadband NIR phosphors with desired properties are decisive for pc-NIR LED devices. Cr³⁺ doped phosphors are considered to be the most promising near-infrared materials for commercialization. Broadband near-infrared luminescent materials doped with Cr³⁺ have attracted more and more attention due to their potential applications in near-infrared light sources. However, the emission wavelength of Cr³⁺ doped phosphors is generally located in the NIR I region of less than 850 nm, and achieving NIR II region emission is still a challenge. In this paper, a series of Cr³⁺ doped Na₃YSi₃O₉ new silicate phosphors were prepared by solid-state method at 1150 ℃ for 8 h in N₂ atmosphere. We take advantages of the silicate nature and the multi octahedral sites suitable for Cr³⁺ in the studied Na₃YSi₃O₉ materials to redshift and broaden the spectrum. The phase, crystal structure, microstructure, photoluminescence, main emission peak decay and thermal stability of the samples were systematically studied. The results show that the prepared samples are pure phases, with uneven morphology and slight agglomeration, and the size is in the order of microns. Cr³⁺ is located in the weak crystal field environment in the Na₃YSi₃O₉ lattice, the Dq/B value is 2.29. Under the excitation of 485 nm blue light, the strongest emission peak of Na₃Y_1-xSi₃O₉: xCr³⁺ phosphors are located at 984 nm (NIR II region), which is longer than most Cr³⁺ activated phosphors. Due to the multi-site occupation of Cr³⁺ in the lattice, the full width at half maximum (FWHM) of the emission spectrum is as high as 183 nm. The optimum doping concentration of Na₃Y_1-xSi₃O₉: xCr³⁺ is 3%, and the quenching mechanism is the dipole-dipole interaction between Cr³⁺ ions. Fluorescence decay curves show that the luminescence lifetime of Na₃Y_0.97Si₃O₉: 0.03Cr³⁺ sample gradually decreases with the increase of doping concentration and temperature. The results of the temperature-dependent spectra show that the emission intensity decreased in the temperature range of 298 K to 423 K, and the activation energy ΔE of Cr³⁺ is 0.157 eV.