针对直扩系统中长PN码同步捕获速度慢的问题，利用推导的串接短PN码与长PN码具有相似相关性的结论，对直扩系统中PN码同步捕获的并行匹配滤波捕获方法进行改进，得到了简单可行的串并结合捕获方法。然后，结合一个周期内PN码相关值，采用迭代的方式，选取简单、实用的自适应门限，实现了突发通信中PN码的快速同步捕获。采用该自适应门限的捕获方法无需估计噪声，计算量小。仿真实验表明所提方法捕获概率高，抗噪性能强。 Abstract: Aiming at slow speed of the long PN code acquisition in DSSS， the similarity between the short PN code in series and the long one can be used to improve parallel digital matched filter（DMF） for the acquisition of PN codes. An improved and simply practiced acquisition method which combine with serial and parallel processing is got. And then a simple and practical adaptive threshold is choosed by using the correlative value of PN code in a period and iterative mode. By using this adaptive method， it is not necessary to estimate the noise and the calculation load is small. Simulation demonstrates that PN codes of the proposed method can be detected at higher acquisition probability and has a better ant-inoise performance.