The artificial anal sphincter (AAS) is permanently exposed to biological tissue fluid after implantation. The design of stable and reliable pressure sensing module plays an important role in the reconstruction of defecation perception and ensuring the safety of blood supply. In this article, based on the characteristics of the acquisition of physiological parameters of rectal pressure, firstly, the material size and other parameters of the sensor are selected through finite element analysis and design, and the slot structure of the sensor installation and the cable trough of the pressure module circuit of the prosthetic arm are designed. The packaging technology and installation method of the new sensor are studied through the experiments on the anti-moisture performance of 9 series of protective adhesives, and a new packaging form is designed for the circuit module of the system, which improves the waterproof performance of the whole system. Experimental results show that the strain gauge resistance of the new sensor changes within 1‰ in the underwater environment for 20 days, the sensor has a high linearity, and the output operating voltage range is appropriate. After the underwater test of the AAS system, the average fluctuation rate of initial sensor voltage is only 4. 1% , which preliminarily verifies the good applicability and application feasibility of the new pressure sensor designed in the vivo environment.