In order to weaken the adverse effects of PV grid connection on the power system and ensure the smooth operation of the system, a novel flexible power point tracking (FPPT) method based on adaptive lion swarm optimization (ALSO) is proposed in this paper. First, a reasonable objective function is established for the FPPT operating mode; the interval optimization method is used to distinguish the operating modes on both sides of the maximum power point (MPP). Secondly, ALSO is used to selectively optimize the operation of different intervals so as to achieve the FPPT control on the left or right side of the MPP. Through the simulation experiments on the PV grid-connected system, the validity and superiority of the ALSO-based method over the traditional FPPT algorithm in terms of dynamic and steady-state performance are verified under different operating conditions.