Abstract: Aiming at the requirement of the data acquisition and program update of underwater unmanned vehicle (UUV), an innovative active sonar data acquisition system for UUV is developed via modularization and hardware/software co-design. The system consists of an active sonar hardware platform with the heterogeneous programmable gate array (FPGA) chip Zynq7020 and host computer software. It effectively fulfills the pivotal roles of data acquisition, storage and transmission. It also provides FPGA firmware online update function. The Light weight IP(LwIP) is utilized in the system to implement the transmission control protocol/internet protocol (TCP/IP). It resolves the data packet concatenation problem, which appears during traditional TCP byte stream transmission, with an application-layer frame protocol based on response mechanisms. This approach could fully leverage the high reliability of the TCP/IP protocol. The test results show that the acquisition, storage and transmission of underwater acoustic data is stably accomplished and software program is online updated while keeping the UUV in the water. It manifests the applied value of the system.