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Spread spectrum ranging technology requires high bandwidth occupation and long duration of PN code acquisition,furthermore,its PN code phase delay problem is serious because of multi-path effect. These factors make it difficult to apply spread spectrum ranging technology in underground coal mines. In order to resolve the awkward situation,a parallel algorithm for PN code precision synchronization was designed making full use of FPGA processor's excellent parallel processing capability . In FPGA,L-1 correlation channels which have a PN code phase differences from each other are allocated,digital baseband signal modulated by PN code is sampled with high sampling after it correlates with the local PN code. This high sampling frequency can greatly improve signal processing bandwidth,so a high time resolution can be obtained only through the coarse synchronization. Experimental results of simulation show that the performance of proposed method can be applied efficiently in coal mine,with high suppression performance over multi-path effect,and the accuracy error of ranging is less than 1 m while the bandwidth occupation of PN code is no more than 50 MHz.