Mars is one of the most valuable planets for space exploration. After entering the entry descent and landing (EDL) phase, the spacecraft would carry out a series of procedural deceleration operations and achieve soft landing on the surface of Mars. In the process of EDL, the landing platform would encounter a series of irreversible incidents within environmental unpredictability, making this process highly risky. The emergency communication device plays an important role if in the Mars Exploration Program. It can capture and store key dynamic parameters during EDL phase, enabling a high probability of survival in the occurrence of a faulty condition. It can also send the stored data to the Mars obit probe when the communication condition is met. This paper presents a scheme design for the emergency communication device based on its functionality and performance requirements. It includes the design proposal, simulation results, reliability analysis, technical risks and control measures, inheritance and performance compliance which verifies the rationality and correctness of the design.