根据弱信号环境中传统捕获算法无法直接捕获到信号的问题，分析了部分算法在捕获灵敏度和捕获效率上的不足。而后根据DBZP (双块补零)算法的分块思想，以及在块内添加FFT模块的基本理念，对信号进行半比特分块进行相邻块的差分运算，并对相邻块进行差分运算，提出并验证一种基于DBZP和半比特交替算法的DBZP-半比特差分算法，既获得了很高的信噪比增益，又保证了捕获速度，同时也降低了频率搜索单元的复杂度。同时就改进方法进行了讨论和仿真验证，能够在实际情况下取得良好的捕获性能。 According to the problem that traditional capture algorithms cannot capture signals directly in weak signal environment, the shortcomings of some algorithms in acquisition sensitivity and acquisition efficiency are analyzed. Then, according to the block idea of DBZP (double block zero padding) algorithm and the basic idea of adding FFT module to the block, the signal is divided into half bits and the adjacent blocks are divided into two blocks. Then, the difference operation is carried out for the adjacent blocks. A DBZP half bit difference algorithm based on DBZP and half bit alternating algorithm is proposed and verified. It obtains high signal-to-noise ratio gain, ensures the acquisition speed of the signal-to-noise ratio, and also reduces the complexity of frequency search unit. At the same time, the improved method is discussed and verified by simulation, which can achieve good capture performance in actual situation.