Abstract: Environmental microvibration affects the accuracy of precision instruments, making microvibration measurement and assessment crucial. Microvibration level measurement is based on the octave spectrum of the velocity signal. However, the frequency-domain FFT method used in traditional octave analysis suffers from shortcomings such as fixed resolution and low-frequency spectrum leakage. Therefore, a complex-analysis ZFFT correction algorithm based on ratio correction was proposed. Simulations show that this algorithm improves spectral resolution while maintaining the same number of FFT analysis points. While maintaining the same number of sampling points, the computational effort is significantly reduced, and the spectrum amplitude error is as low as one thousandth. Frequency-band octave analysis is employed to suppress low-frequency spectrum leakage and increase the number of spectral lines. A microvibration monitoring and analysis system was developed, comprising a low-frequency microvibration sensor, the MI-7208 intelligent measurement device, and microvibration level measurement and assessment software. Field measurements verified the system's ability to detect VC-F-level microvibration signals and its long-term measurement stability.