A spread spectrum PRMA(SSPRMA)with randomized arrival time is proposed in this paper.We analyze its channel utilization and the probability of voice packet being dropped(Pdrop) by Markov chain analysis. We derive a formula that can be used in the calculation of the Pdrop of SSPRMA. It can also be used in the calculation of the Pdrop of PRMA if the number of address codes of each slot is 1. This problem is not solved in Reference[4]. We exploit the delay cape phenomenon to improve the performance of this protocol. Packet transmission errors are taken into account in the simulation and the Markov chain analysis. Numerical results prove that delay capture phnomenon improves the performace of SSPRMA.