A ManchesterⅡdecoding system based on DSP was developed to increase it’s flexibility, accuracy, and reduce hardware cost. On the basis of analyzing the characteristics of ManchesterⅡsignal entirely, ManchesterⅡsignal which is transact by logging cable and processed by conditioning circuits, limiting amplifier circuit, shaping circuit and positive and negative pulse separation circuit can be captured by DSP’s pulse capture units, then be decoded by software algorithm. Experimental results show that design of Manchester II decoding system based on DSP is reasonable and can be satisfied with requirement of production logging and conventional logging.