Abstract: We propose an Low Delay sleep Scheduling algorithm base on Contact Probability for opportunistic networks(LDSCP).Algorithm predicts the next wakeup time through the accurate prediction mechanism. This mechanism predict the next wakeup time before and after the current wakeup time which missed encounter with the expected node, so it can ensure the accuracy of prediction at the next encounter. And when the wakeup time is overlapped with each other, the algorithm uses the probability maximization mechanism to increase the chance of encounter and reduce the message delivery delay. Theoretical analysis verifies the effectiveness of LDSCP. Also, Simulation results show that LDSCP outperforms the WS algorithm and the classical epidemic algorithm in terms of message delivery success ratio, average end-to-end delay, message average transmission hops.