The invention relates to an alignment adjusting device of optical fiber collimators. A distance adjusting guide rail mechanism and an alignment adjusting guide rail mechanism, which are perpendicular to each other, are arranged on a base, and an extension line of the distance adjusting guide rail mechanism is intersected with the alignment adjusting guide rail mechanism, so the movement locus of a distance adjusting sliding block and an alignment adjusting sliding block is T-shaped, and fastening structures which are consistent in height and used for paralleling or overlapping the extension directions of the optical fiber collimators are arranged on the distance adjusting sliding block and the alignment adjusting sliding block. Therefore, when the alignment adjusting device is used, on the premise that two optical fiber collimators are consistent in height and the extension directions are parallel or overlapped, distance and alignment are adjustable, so the problem of difficulty in alignment of the optical fiber collimators in the prior art is solved.