Today, the technology of extrusion 3D printing of plastic products is developing at the highest rate, due to its availability. Therefore, the creation of composite materials, based on thermoplastics, which contain various additives, aimed at improving the physico-mechanical and aesthetic characteristics is becoming more important. In this regard, the studies on the effectiveness of using a thermally modified wood filler in the filaments, used in extrusion 3D printing technologies, were conducted in this work. It was found that the presence of a thermally modified wood filler reduces shrinkage of the composite and allows obtaining products with the smallest surface roughness. However, with a high content of filler in the composite, a decrease in its strength properties is observed.