Lattice Optimization of BEPCII Collider Rings

BEPCII is a double ring e⁺e⁻ collider operating in the tau-charm region. In March 2013, the peak luminosity achieves 7.0·10³² cm⁻²s⁻¹ with a new lower alphap lattice. The beam-beam parameter is also increased from 0.033 to 0.04 with the new lattice. In this paper we'll review the lattice optimization history briefly and focus on the optimization of the lower alphap lattice.