Abstract: Distress beacon is an important part of the global satellite search and rescue system (COSPAS-SARSAT). However, most of the distress beacons at present are first-generation narrowband beacons, which adopt fixed modulation frequency conversion architecture, and have defects of low integration, single function, hardware circuit replacement and so on. In order to solve these problems, based on ZYNQ7000+AD9361 software defined radio integrated architecture, a second-generation of distress beacon signal generating circuit is designed in this paper, with which the information content, signal format and transmission parameters can be flexibly defined by software. According to the format specification of the second-generation distress beacon signal of COSPASSARSAT system, signal processing processes such as spread spectrum, filtering and modulation are first designed in this paper, and signal characteristics are simulated and verified. Then, ZYNQ7000+AD9361 software define radio architecture is used to complete the PL and PS design, realizing the transmitting signal in accordance with the second-generation COSPAS-SARSAT beacon standard. Finally, the test results show that the design method effectively and feasibly meets the design requirements. The design has the advantages of few discrete devices, high integration, high programmability, and flexible realization of online maintenance and upgrading of beacon and signal conversion.