In the controlled environment of mushroom cultivation room, Pleurotus ostreatus was grown under different LED red-blue light treatments based on light intensities of 15μmol·m−2·s−1 and 7μmol·m−2·s−1. The treatments included continuous pure red light (R15, R7), continuous pure blue light (B15, B7), continuous red-blue mixed light (R7B7), intermittent red light (R-7), and intermittent blue light (B-7), with natural indoor light at an intensity of 1 μmol·m−2·s−1 as the control group (CK). The study aimed to investigate the effects of different LED red-blue light supply modes on the fruiting, spectral characteristics, and mineral nutrition of Pleurotus ostreatus, providing reference for light environment regulation in industrial cultivation of Pleurotus ostreatus. The results showed that: (1) the Pleurotus ostreatus yield of B7 and B15 treatments increased by 37 and 23 percentage points, respectively, compared to the control group. The B7 treatment promoted an increase in cap width by 13.19% compared to the control group, while the R15 treatment promoted an increase in stem length by 18.24% compared to the control group. The B7 and B15 treatments resulted in higher yields of Pleurotus ostreatus, with yields of 295g and 300g per bag respectively. (2) Compared to the control group, the B7 and B15 treatments increased the color saturation (C value) and Hue angle (Hue value) of Pleurotus ostreatus fruiting bodies. C value increased by 72.00% and 53.74%, respectively, compared to the control group, while the Hue values increased by 0.23% and 0.19% respectively compared to the control group. Overall, blue light was more conducive to the coloration of Pleurotus ostreatus. (3) Compared to the control group, all treatments increased the content of trace elements in the cap of Pleurotus ostreatus. The increases in P, K, Mg, Mn, and Zn were 29.55%−107.32%, 30.74%−75.60%, 16.19%−57.14%, 23.72%−93.26%, and 15.23%−130.42% respectively. Of these, the R7B7 treatment increased the content of these five elements by 104.26%, 75.6%, 55.24%, 93.25%, and 96.31% respectively compared to the control group. Mg content in the stems of Pleurotus ostreatus decreased by 3.33%−27.73% in all light quality treatments. In summary, continuous pure blue light is beneficial for increasing the fruiting rate, cap width, stem diameter, and yield of Pleurotus ostreatus, as well as enhancing its coloration. A continuous mixture of red and blue light favors the accumulation of mineral elements in Pleurotus ostreatus. Therefore, light environment regulation can be adjusted according to actual production conditions to promote high-quality and high-yield cultivation of Pleurotus ostreatus in facilities.