Abstract: The object of this research was to provide a new approach for improving the adhesion performance of UF adhesive by modification with a small amount of soy protein. The optimum addition level of soy proteiniselate(SPI), as well as the adhesion performance, such as the bonding strength, free formaldehyde content and conformation change of SPI/UF adhesive had been investigated by the orthogonal balance block test of L₉(3⁴).The thermal performance of SPI/UF copolymer resin was characterized by differential scanning calorimetry, and the biodegradability of SPI/UF resin was preliminarily analyzed. The results showed that the bonding strength of SPI/UF resin was 1.16 MPa in the condition of hydrolysis at 85 ℃ for 40 min and urea substitution ratio of 15% by SPI. Thermal stability of the resin increased through SPI modification. A small amount of fungus colonies had become visible in the surface of SPI/UF resin after inoculation of microorganisms, which indicated the modified resin had gained a certain degree of biodegradability.