Abstract: The paper studied the Maillard reaction and products properties at different SPI-COS mixing ratio in the dry heat state. The Maillard reaction was monitored by absorbance at 420 nm and 290 nm, changes of free amino acids, furosine and 5-hydroxymethyl furaldehyde. Meanwhile, Zeta potential, solubility,emulsification, thermal properties and fluorescence intensity of the Maillard reaction products were characterized as well. The results indicated that the Maillard reaction between SPI and COS increased with the increase of COS ratio. Compared with SPI-COS mixture, the Zeta-potential, solubility,thermal stability of Maillard reaction products of SPI and COS decreased, and the zeta potential reached the minimum value of −33.8 mV at 8:1.When the mixing ratio of SPI and COS was 8:1 and 4:1, the emulsion activity and emulsification stability of the system were the optimal, which were improved by 509.3% and 183.3%, respectively. Therefore, the Maillard reaction between SPI and COS has effectively improved the emulsifying ability of SPI, which is expected to gain wide applications in the food industry as a novel emulsifier.