A new approach to numerical simulation of double-crystal rocking curves is proposed. This approach is based on the use of experimental spectral angular diagrams of X-ray intensity distribution. Special calculation algorithms, which take into account the instrumental function of X-ray diffractometer and possible effects of dispersion and Bragg reflection asymmetry, have been developed and applied. A specific feature of the proposed approach is the possibility of visualizing the 2D spectral angular diagram of X-ray beam after its interaction with each element of the scheme. The approach makes it possible to perform calculations for a wide range of radiation sources (from an X-ray tube with any anode to a synchrotron radiation source) and X-ray optical elements (slits and monochromators). A comparison of simulation results and experimental data for a Si(110) crystal sample has confirmed adequacy of the proposed approach and its applicability for simulating diffraction patterns recorded in real experiments.