A 1×2 array Dammann grating beam splitter for implementation of frequency resolved optical gating (FROG) is proposed. Beam splitting with Dammann grating can avoid the material dispersion in traditional beam splitters. The measuring result by the newly established FROG is compared with that of a traditional multi-pulse FROG. Theoretical and experimental results show that when the input pulse width is larger than 50 fs, the pulse broadening introduced by Dammann grating and general beam splitter is almost identical; but when the input pulse is shorter than 50 fs, the broadening effect of Dammann grating is obviously less than that introduced by general beam splitter, especially for laser pulses shorter than 20 fs.