This paper describes a System-on-Chip(SoC) for pressure balance measurement in total knee arthroplasty (TKA). This SoC consists of 8051 processor, ADC, RF transceiver with 3Mbps MSK transmitting and 64kbps OOK receiving, SPI interface for transmitting the data between the SoC and EEPROM, SRAM acting as memory buffer and some other peripherals. Fabricated in 0.18μm CMOS, the area of the SoC with pads is up to 3 mm2*3 mm2.