We analyzed the effect of various normal distributed nonuniformities of sampled fiber Bragg gratings on the reflective spectra and group time delay. Through numerical simulations, we have drawn the following conclusions: (1) the magnitude of nonuniformity with normal distribution of fiber average refractive index modulation δneff greatly influences the characteristics of both reflective spectra and group time delay, and the suggested precision of that varies from 20% to 10%; (2) the nonuniformities of sampling periods P and sampling lengths L are very important factors that influence the characteristics of the group time delay, and the accepted tolerance of dimensional precision of both sampling period P and sampling length L are about ±4 microns; (3) the tolerance of the nonuniformity of the sampling period’s chirp coefficient cs is high, and its precision can be as great as 100% with small adverse effects.