Abstract: Under the frame of time-dependent density functional theory( TDDFT) and molecular dynamics,we studied microscopic electronic-ionic association dynamics in collision between hydroxyl and proton which moves toward molecular axis of hydroxyl with 15 eV initial kinetic energy. Energies of projectile and target,electron and vibration excitations of target and real time distribution of electron density are identified. It is found that proton captures electrons of hydroxyl in collision and it rebounds from the target with loss of 26.7% of initial kinetic energy. While the kinetic energy of hydroxyl increases and hydroxyl moves toward to numerical boundary accompanied with stretch oscillation. Hydroxyl loses 1% electrons and exists as neutral and ＋1 valence forms with 93% and 7%probabilities respectively.