Abstract: The corn straw had been treated with HCl, NaOH, hydrothermal, carboxymethyl cellulose(CMC) and pectin in this study, and then lightweight corn straw boards were fabricated by hot pressing technology. The effects of single factor treatment and combined treatments on the surface wettability, surface microstructure, thermal stability and mechanical properties of the corn straw board were investigated. The results showed that single-factor pretreatment can reduce the contact angle of corn straw fiber. Corn straw surface morphology changed from smooth to rough after pretreatment, along with fractured surface and significantly decreased of silicon element mass fraction. Corn straw treated by NaOH had the best surface wettability. Thermal stability analysis indicated that corn straw with pretreatment had no significant thermal decomposition in the hot-pressing temperature of 150 ℃. All pretreatment can effectively improve the mechanical strength of corn straw board but combined pretreatments does not further improve than single factor pretreatment. HCl, NaOH and hydrothermal pretreatment will weaken the structure strength of corn straw fiber. The effect of pretreatment on mechanical properties of fiber structure strength is greater than the bond strength of interface. Hydrothermal pretreatment has the best performance to improve the mechanical properties of corn straw board, and IB increased by 700.0%, MOR increased by 112.5%, MOE increased by 87.5%.