The paper presents the results of a comparative study of the physics and mechanical, rheological and biodegradation characteristics of composite materials based on a mixture of polyethylenes of low (LDPE 273-83) and high (HDPE 15303-003) pressure in a ratio of 1 : 1. The composite was also filled with finely ground wood flour with a particle size of less than 200 microns (5-30% by weight) and 10% compatibilizer (functionalized by the alkaline alcoholysis splitting method of sevilene (EVA 12206-007) and a processing additive of 1% polyethylene glycol (PEG-115 (4000). It has been found that with an increase in the content of wood flour (up to 20%), the modulus of elasticity and ultimate strength practically have not changed. The tensile elongation of the composite exceeds 100% (if the content of wood flour is up to 15% by weight). The complex viscosity and shear modulus of the considered melts with different filler contents are practically at the same level. At the same time, the introduction of wood flour up to 30% and a compatibilizer (10%) promotes a slight increase in the viscosity and elasticity of melts, which practically does not affect the change in the manufacturability of the compositions in comparison with LDPE 273-83. For a comparative assessment of the ability of composites to biodegradation, moisture absorption, chemical oxygen consumption, and weight loss of composites in laboratory soil during exposure for 12 months were studied. It has been shown that as the filler content increases, the biodegradability of composites increases.