Abstract: In order to expand multi-function and high-value application of wood, balsa wood was used as raw material. Firstly, they were performed with chemical treatment to remove the matrix including lignin and hemicellulose, followed with drying. The acetylated balsa wood frame (AWF) was prepared by acetylation modification. Afterwards, by vacuum impregnation, polydimethylsiloxane (PDMS) elastomer was introduced into balsa wood frame (WF) and AWF respectively, in order to fabricate composite film materials (PDMS/WF and PDMS/AWF). The effects of acetylation modification on morphology, mechanical properties, chemical composition and surface hydrophilicity of composite films were systematically studied. The results show that after acetylation, the interface between balsa wood frame and PDMS is more compact, and the pores between PDMS and white wood are smaller. At the same time, the tensile strength of PDMS/AWF composite film (along the fiber growth direction, L-direction) is around 176 MPa, and the toughness is about 6.58 MJ/m³, which is nearly twice as high as that of PDMS/WF compo-site film. Furthermore, the prepared PDMS/AWF wood-based composite film was used as a flexible substrate to assemble a flexible sensor. As a result, it shows stable and repeatable changes for relative resistance values under various deformations. Altogether, it has great potential to be applied in the research fields of smart furniture, elastic substrates of smart response devices, flexible electronic components and wearable devices.