The work aims to modify copper-based preserved wood mildly through the sol-gel method to improve the properties of active ingredients in copper-based preserved wood. With poplar wood as the research object, and ethyl orthosilicate as the precursor, the effects of two sol-gel methods, direct impregnation and in situ fixation, on the properties of specimens impregnated with ACQ preservative and CA preservative were investigated respectively. The results showed that both sol-gel methods could form a silica mesh structure in the conduit of poplar wood, which in turn increased the fixation rate of copper ions in the preservative by 2%-9%. As shown by the results of the performance tests on the contact angle, thermal weight and mildew protection, both sol-gel methods can improve the hydrophobicity, thermal stability and mildew protection of the wood, and have a better modification effect.