Abstract: Low-rank coal is characterized by a low degree of coalification, abundant surface oxygen-containing functional groups, and poor hydrophobicity, which lead to high dosages of traditional hydrocarbon oil collectors and poor flotation performance. To address these issues, a novel composite collector (MBSG), composed of non-polar and polar molecules, was developed. Advanced analytical techniques—including Fourier Transform infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), contact angle measurement, and flotation kinetics tests—were employed to investigate its influence on the flotation performance of long-flame coal. The results indicate that the surface of long-flame coal is rich in oxygen-containing functional groups. Through synergistic adsorption, MBSG reduces the relative content of these functional groups on the coal surface, effectively enhancing its surface hydrophobicity. Under the optimal flotation conditions (impeller speed of 1800 r/min, aeration rate of 0.2 L/min, pulp concentration of 80 g/L, and MBSG dosage of 1.0 kg/t), the clean coal yield reached 30.63% with a combustible recovery of 80.52%. Notably, the collector dosage was reduced by more than 90% compared to traditional diesel. The findings demonstrate that MBSG can effectively improve the floatability of long-flame coal, providing technical support for the clean and efficient utilization of low-rank coal.