A RFID reader baseband for multi-protocol with universal transmitter is presented in this paper. In order to support multi-protocol, a universal transmitter is designed, and the receiver can support FM0 and Miller with different value of M decoder of a variable rate. In addition, an MCU of DW8051 which is used to configure the value of registers to achieve the functions is embedded in this chip. The whole reader is fabricated in 0.18μm CMOS technology, and the area of digital baseband is 4.4mm2, including the MCU and memories. The power of digital baseband is 220μW in post-layout simulations.