DSP has been widely used in various information systems and interintegrated circuitl I²C bus is a popular communication bus used to communicate between different chips. Therefore it is very important to effectively design an interface between DSP and I²C. Through the deep analysis of the writing and reading time diagrams of DSP and I²C bus, a solution (hardware and software design) to implement I²C interface based on DSP is proposed. By use of the external memory interface of DSP,fliplatch and buffer, DSP can be communicated with I2C devices correctly. The writing and reading flow of I²C devices are controlled by software and high reliability is achieved through simple hardware devices. The example of TMS320C80 DSP is also proposed. 