The Ptychography algorithm can be implemented to realize the super-resolution reconstruction of ultrashort pulses when the frequency-resolved optical gating (FROG) method is used for their diagnosis. We obtained an arbitrary FROG trace by multiplying matrices, exploited the extending property of “sinc” functions, and then demonstrated the coding phase principle of the FROG method. The proposed analysis provides theoretical support for the super-resolution reconstruction of ultrashort pulses. Furthermore, a numerical simulation revealed the phase recovery results of the Ptychography algorithm with undersampling in both the delay axis and frequency axis of FROG trace. These results are conducive for making the FROG measurement more accurate and less time-consuming.