According to the special requirements of detection and data compression for the 50Hz fundamental short duration voltage variation signals to the wavelet basis, the best effective wavelet basis db4 was gotten using simulation experiment, which had excellent performance both on detection and digital fault data recorded compression decompression. The db4 was applied for time-frequency analysis of short duration voltage variation signals, to accurately estimate the starting and ending moments and amplitude of the short duration voltage variation, and digital fault data recorded compression and decompression is achieved. principles of the wavelet transform were briefly introduced, algorithm simulation and the system block diagram were given. Simulation experiment results verify the feasibility and accuracy of this algorithm. Moreover, a signal occurrence and detection system of short duration voltage variation based on LabVIEW was developed. The operation results show that system is easy to operate with accurate and reliable measurement excellent performance.