Using the projection and Fourier transform methods,we have derived the diffraction formulas and discussed the rules of diffraction peaks and systematic absences for the one-dimensional Fibonacci-class quasilattices.Moreover,we have calculated and labeled the positions of the diffraction peaks of FC(1) and FC(3).In order to check our diffraction formulas,we extend the formulas to the FC(n) quasiperiodic superlattices.Comparing the present diffraction results of the FC(1) superlattice with the experimental data,we have found that most of them agree with each other but one of the spectra is not consistent.Particularily,we doubt that the peak (4,2) in the experiment should be a stronger peak.