The interference of several optical vortices can generate intriguing intensity and phase distributions due to the particular helical phase structures and central singularities. The interference of optical planar vortex, which has a phase singularity and a dark hole nested in an infinite plane-wave background, is simulated. The influences of the distances between the singularities and the topological charges of two planar vortices on the annihilations and creations of vortices are analyzed, respectively. Further, the interference of the symmetric point vortices is investigated numerically. The results show that a rich variety of the symmetric vortex arrays can be obtained by changing the number of the vortices and/or the topological charges. The interference of the symmetric point vortices is demonstrated experimentally by utilizing computer-generated holography and spatial light modulator. The experimental results are in good agreement with those of numerical simulation. It not only confirms the numerical results, but also demonstrates a convenient way of generating interference of complex optical vortices.