The performance of mode diversity combined with adaptive optics (AO) based on a multipath stochastic parallel gradient descent (SPGD) algorithm over free-space optical (FSO) links through atmospheric turbulence is presented. The experimental results indicate that, compared with a single-mode fiber (SMF) combined with a single-path SPGD algorithm, three modes diversity combined with a multipath SPGD algorithm effectively reduces the power fluctuation. When the sensitivity of the receiver is assumed, the outage probability for the FSO system based on mode diversity is superior to that of the FSO system based on a SMF. The reduction of outage probability arising from mode diversity is more significant when AO is implemented. To the best of our knowledge, this is the first time that the performance of modes diversity combined with a multipath SPGD algorithm over a turbulence channel has been studied.