This paper presents the design of a wireless capsule endoscopic system with a low-power controlling and processing ASIC. The system aims at several design challenges including system power reduction, system miniaturization and wireless wake-up method. These challenges are met by employing optimized system architecture, integration of an area and power efficient image compression module, a power management unit (PMU) and a novel wireless wake-up subsystem with zero standby current in the ASIC design. The ASIC has been fabricated in 0.18-μm CMOS technology, and occupies a die area of 3.4mm*3.3mm. The digital core can work under a power supply down to 0.95V, and the power consumption is only 1.3mW. The wireless capsule endoscope prototype has been implemented with this ASIC.