In terms of Fourier optics, a single-pass tiled-grating compressor based on in-pair compensation is studied and the amplitude expression of the output pulse from the compressor in the far-field is obtained, which disclose that effect of the group delay, the pulse front tilting and the residual chirping on the pulse-width in the far field. Numerical simulation shows that the pulse in the far field is broadened with increasing spectral width. For a typical single-pass tiled-grating compressor, the tolerance of each error is obtained and the allowed spectral width is obtained when all errors are considered.