A new strategy for designing and synthesizing carbon quantum dots with selective detection of metal ions using biomass sugarcane bagasse as a carbon source to obtain high photoluminescence sugarcane bagasse carbon quantum dots. Nitrogen phosphorus doped carbon quantum dots (N/P-CDs) were prepared by in-situ doping one-step hydrothermal method using diammonium dihydrogen phosphate as nitrogen and hosphorus sources. The morphology, structure, and fluorescence properties of doped carbon quantum dots were characterized by FL, XRD, UV-Vis, FT-IR, AFM and PL. The results showed that by controlling the mass ratio, hydrothermal reaction temperature, time, and material mass ratio, the absolute quantum yield of N/P-CDs reached 14.6%, with a size of approximately 10 nm. N/P-CDs exhibit excellent fluorescence erformance, exhibiting blue fluorescence under UV irradiation at a wavelength of 365 nm. Their maximum excitation wavelength is 330 nm and emission wavelength is 407 nm, showing sensitivity to Fe3+. A new strategy for preparing high photoluminescence carbon quantum dots by doping sugarcane bagasse with N and P elements has been proposed, which can provide a certain foundation for the high-quality utilization of sugarcane bagasse.