Abstract Applying generalized vortex theory for inhomogeneous superconductors [B.J. Yuan, Z. Physik B 96 (1994) 165; B.J. Yuan, Z. Physik B 98 (1995) 457] to a large but finite geometry, a theoretical solution for vortex lattices is presented in this article. By requiring magnetic flux conservation in a superconductor within the finite geometry, the theoretical solution describes symmetry variation of vortex lattices with respect to varying strength of applied magnetic field. The theoretical results are consistent with the experimental observations reported in cited references.