The axial resolution of optical coherence tomography (OCT) depends on not only the bandwidth of the light source but also the dispersion balance between the sample arm and reference arm. If the dispersion between two arms is not matched accurately, the axial resolution of optical coherence tomography system will degrade. Dispersion problem is very important especially in ultrahigh resolution optical coherence tomography system. A method for dispersion compensation in optical coherence tomography by a double-grating based rapid scanning optical delay line (RSOD) is put forward. The independent variable of the distance between gratings in the added gratings, along with the adjustable distance between grating and Fourier transform lens in a conventional rapid scanning optical delay line can be used to compensate the group velocity dispersion (GVD) and third order dispersion (TOD) of optical coherence tomography system simultaneously. The dispersion characteristics as well as the dispersion management scheme are discussed. Example of dispersion compensation in a typical optical coherence tomography system is provided.