In order to break through the bandwidth limitation of digital instantaneous frequency measurement for a real-valued waveform, we developed a frequency estimator with a high dynamic range and low computation cost using multiple sub-Nyquist ADC channels. The procedures of the proposed scheme are as follows: 1) Perform zero-crossing detection on the real-valued signal and use multiple sub-Nyquist ADC channels to sample the output signal; 2) Take several samples of each channel to calculate the folded frequency; 3) Use the frequency residuals of each channel to reconstruct the frequency based on the Chinese remainder theorem. Finally, the algorithm robust analysis and simulation experiments are performed, demonstrating that the scheme of this paper has relatively good anti-noise ability and dynamic adaptability.