In view of the high uncertainty and slow acquisition speed of signal frames in small local area networks, a new method for fast acquisition of frame signals in small range local area networks is proposed in this paper. The frame generation and resource mapping process of small local area network are introduced. FFT method is used to calculate the data after Q processing, and compare the obtained value with the given threshold to judge whether to go to the tracking state. The flow chart of FFT PN code acquisition method is given. The pseudo code search in frequency domain is completed by the parallel local correlation and the FFT principle, and the frequency difference between the local carrier and the received signal carrier is determined, and the corresponding correction is completed. The two-dimensional search of carrier and pseudo code is converted into one dimensional detection cable, and the frequency difference between them is determined. Experimental results show that the proposed method has low complexity, high acquisition accuracy and fast acquisition speed.