Abstract: This paper presents a method to calibrate mobile robot wheel-slippage by encoders and electronic compass when the mobile robots isn't distorted by magnetic interference. A model for wheel-slippage is defined, which can judge whether the driving wheels have slippages. Based on this model, an algorithm is proposed to determine which driving wheel has slippage and to calibrate the resulting orientation error and displacement error when wheel-slippage occurs. Experimental results show the validity of the method.