In order to improve the acquisition speed and accuracy of global positioning system (GPS) software receiver, an improved orthogonal search precise acquisition method is proposed. Firstly, the correlation acquisition results of GPS signals are used to remove the code phase, and an alternative set of functions is constructed. Then, based on signal decomposition theory, the precise acquisition of signals is realized by orthogonal search. The orthogonal search method is improved, and the iterative search strategy is adopted to improve the acquisition speed. The theoretical analysis and experimental results show that this method can achieve high precision estimation of precise acquisition frequency of GPS signal, and the convergence speed of precise acquisition is very fast, which can effectively reduce the resource consumption of GPS equipment.