Abstract: For problem that current harmonic detection and analysis devices are too expensive, a simple on-line harmonic detection and analysis system was designed. The system uses digital signal processor TMS320F2812 to build circuit of harmonic detection device, which could collect and transmit harmonic data fast, and adopts LabVIEW virtual instrument to develop upper computer system, which could display detected harmonic real-timely and do harmonic FFT analysis. The system has simple structure and convenient operation. The experimental result showed validity of the system.