Abstract: Data bus consumes a large amount of energy in the system-on-chip. This paper proposes a novel data bus encoding with low coupling transitions to save the data bus power dissipation. The encoder utilizes the previous data on the data bus to encode the current data with XOR and XNOR operations, and chooses the data with minimal coupling transitions among XOR encoding data, XNOR encoding data, invert encoding data and the original data to send on the data bus. This method can reduce a majority of data bus coupling transitions, thus saving the data bus power dissipation significantly. Experimental results show that this method could save 33.06% of the common 32-bit data bus power dissipation, superior to the traditional CBI encoding and E/O BI encoding