Abstract: For the purpose of detecting the dynamic viscoelasticity of wood composites which is one of several important indicators to characterize mechanical properties, five sets of commercially purchased thin wood composites having four different fiber types were selected as experimental materials. Using a mechanical property analyzer which was newly self-developed, the first order frequency of the specimen cantilever vibrating and logarithmic decrement of the vibration waveform were measured to calculate the dynamic viscoelasticity including the storage modulus and loss modulus. The dynamic viscoelasticity of the same specimens was also detected by the conventional method based on forced vibration. The results showed that there was a very significant linear correlation between them. It was feasible that the detection method of the dynamic viscoelasticity of the thin wood composites based on the principle of cantilever-beam free vibration.