In ultrafast laser-matter interaction experiments, single-shot, real-time spectral interferometry is the significant for rapid and accurate measurement. Based on spectral interferometry and time-frequency linear relation of linearly chirped pulse, the method that spectral phase-shifts of chirped pulse are transformed to temporal phase-shifts in a directly frequency-to-time mapping mode is investigated theoretically. Restrictive conditions of this method are derived. The transformation process of phase-shifts is simulated. The results show that phase-shifts obtained is characteristic of temporal change, and this approach has single-shot measurement ability, which in perturbation and fixed pulse bandwidth, the transformation error of phase-shifts is reduced, as appropriate increase of the chirp of probe pulse.