This paper introduces an online system for detecting the strength of Laminated Veneer Lumber with vertical vibration methods. This system uses an acquisition card which type is PCI-1710HG developed by Advantech to collect data. Also it processes data with industrial computer. By computing the vibration signal’s logarithmic attenuation rate and dynamic elastic modulus the system can achieve the online nondestructive strength detection of LVL. This paper mainly discusses the system’s detection principle and detection methods, also it gives the hardware structure and software design. The system has been tested and verified by the experiment.