Abstract: A series of NaMgBO₃∶Ce³⁺/yYBO₃∶Ce³⁺ (composite ratioy=0~0.035, mole ration) phosphors were prepared by a second-phase composite method, and their phase, morphology and optical properties were investigated. When YBO₃∶5%Ce³⁺ was chosen as the complex substrate and composited into the NaMgBO₃∶Ce³⁺ phosphor, the band gap of the sample increased, and the emission intensity of the sample at 464 nm was gradually enhanced with the increase of the YBO₃∶Ce³⁺ composite ratio, and the optimal ratio y was 0.025. Since the emission peak of YBO₃∶Ce³⁺in the range of 380-400 nm overlaps with the NaMgBO₃∶Ce³⁺ excitation peak, and the emission intensity of the composite sample in this range will decrease with the increase of the mass concentration of YBO₃∶Ce³⁺, which proves the existence of energy transfer between YBO₃∶Ce³⁺ and NaMgBO₃∶Ce³⁺. The results show that this phosphor can be a good candidate for cyan filling in full-spectrum illumination.