The invention discloses a sound-wave-based square wood hole-defect 
recognition system and a sound-wave-based square wood hole-defect recognition method, which mainly solve the problem of difficulty for nondestructive detection of a hole defect of square wood. The 
system comprises a small hammer, a 
sound wave signal acquisition module, a 
sound wave signal processing module, a NiosII processor, an 
external storage module, a 
USB (universal serial 
bus) communication module and a principal 
computer processing module. The 
sound wave signal acquisition module is used for completing the sound wave acquisition, AD conversion, amplification and low-
frequency filtering; the sound wave 
signal processing module is used for driving the acquisition module and 
processing a sound wave 
digital signal; the 
external storage module comprises an SDRAM (
synchronous dynamic random access memory) and an EPCS (electronic propulsion 
control system) configuration memory; the NiosII processor is used for 
processing and caching the signal and calling the 
USB communication module to upload the data to the principal 
computer processing module; a sound wave signal time-domain and frequency-domain waveform characteristic value is extracted from the principal 
computer processing module, and the defect is recognized by adopting a 
fuzzy model recognition method. The 
system and the method are 
pollution-free, harmless, simple and convenient to use, high in recognition rate and suitable for detecting the hole defect of the square wood, and the detected wood is not damaged.