In this paper, an indoor positioning scheme is proposed: using infrared as the synchronization timing signal of the ultrasonic signal, the internal multichannel counting module of the FPGA synchronizes the ultrasonic count and uploads the sampled data to the master chip STM32 through the SPI bus. The data is further processed, and finally the position of the target point is obtained by the positioning algorithm. The main function are FPGA multichannel signal acquisition, FPGA and SPI communication design and positioning algorithm design, which has a high reference value in practical application.