The invention discloses a device for measuring group delay dispersion of biological tissues by combining FDOCT. A frequency domain optical coherence chromatographic system of the device comprises a laser source, an optical fiber coupler, a first collimating lens, a second collimating lens, a second galvanometer, a lens, tested tissues, a third collimating lens, a second optical grating, a second fourier lens, a CCD and a signal processing system, a rapid scanning delay line system comprises a bipass reflecting mirror, a first galvanometer, a first fourier lens and a first optical grating. When dispersions between a reference arm and a sample arm of the FDOCT system are not matched, the system resolution is reduced; tissues are respectively imaged by regulating the dispersion values of the distance between the optical gratings and the fourier lenses in the introduction of linear change of the reference arm of the system, and the dispersion value of the reference arm introduced when the resolution of the upper and lower interface of every-layer tissues is the highest is extracted correspondingly, so that the difference of the two values is the dispersion value of the tissues on the layer. According to the device and the method, tested parts are not required as section samples, the working efficiency is improved and the pain of patients can be reduced.