in this study, the effects of oleothermal modification on physical and mechanical peroperties of fir wood (abeis sp.) blocks were examined. at first, some blocks of fir wood with 5 × 20 × 120 cm dimensions were prepared. the blocks were treated in soybean oil. the effects of 3 factors such as treatments temperature (180and 200 °c), holding time (12 and 15 h) and initial moisture content of wood(8 and 28 %) on physical properties, such as collapsing of blocks,oven dry density, water and moisture absorption and subsequent swelling and mechanical properties; such as bending strength, compressive strength, hardnessjanka as well as non-destructive evaluation methods were considered (vibration and stress wave). the results showed that oil heat treatment caused the increase of density of fir woods. also oleothermal modification decreased the water and moisture absorption by fire wood. increasing of temperature and time of treatment improve these characteristics, indeed the dimensional stability of sample also significantly improved. there was no significant difference between mechanical characteristics of oleothermally modified and control woods. non-destructive test samples showed that these treatments increased the dynamic modulus of elasticity of the samples. final results showed that oil-heat treatments improved physical and some mechanical properties of fir wood.