The presence of malachite green dye in wastewater has a great negative impact on the environment. At present, industrial wastewater is treated using adsorption, electrolysis and membrane separation, among which the adsorption method is the most widely used wastewater treatment. In this study mesoporous silica nanoparticles (MSNs) were prepared using the sol-gel method and modified with the natural polymer urushiol (U) to obtain MSN@Us, which have a core-shell structure. This is the first use of urushiol in dye adsorption. The structures and chemical properties of the MSNs and MSN@Us were characterized. The adsorption of malachite green by the MSNs and MSN@Us showed that the adsorption rate of MSN@Us was higher than that of MSNs, with an adsorption rate greater than 90%. This study provides a new research direction for the use of urushiol in the treatment of contaminated wastewater.