Phase synchronization in coupled chaotic systems is an interesting topic in recent years on nonlinear dynamics. Phase synchronization implies an ordered behavio r embedded in chaotic motions. Recent progress on phase synchronizations is revi ewed.The synchronization process is exhibited by applying the bifurcation tree.T he synchronization process is identified as transitions from high-to low-dimensional chaos.An alternative phase locking among various rational ratios is found. Chaos suppression and the restoration to chaos synchronization via period-doubli ng is studied.It is found that asymmetric coupling can greatly enhance the phase synchronization of coupled oscillators.