A high-resolution real-time time-frequency domain measuring device includes a light splitting unit used to split signal light to be measured, a time lens unit used to perform time domain amplification on the signal light to be measured, a dispersion Fourier transform unit used to perform Fourier transform on the signal light to be measured, and a detection unit used to receive and detect measured data. The time lens and the dispersion Fourier transform technology are used to realize the real-time measurement of sub-picosecond transient characteristics of the ultra-short pulse to accurately obtain the time-frequency domain information of the ultra-short pulse.