The coupling relation between heartbeat and respiration for the youth after exercise is investigated. We use empirical mode decomposition method as a filter to analyze the data of heartbeat and respiration obtained. It is shown that the cardiorespiratory phase synchronization still exists after exercise. Moreover, the ratio of phase-locking is different for different people and changes along with time. We proposed a measure of coupling relation based on transfer entropy, and found the coupling effect of respiration on heart is relatively large.