The measurement of translational motion is widely applied to many fields such as machine vision, automatic control, etc. A new measurement system of 3-D (three dimensions, X, Y and Z direction) translational motion based on twin area array CCDs is designed. The system consists of stationary part and moving part. The stationary part mainly includes two collimated LED (Light-Emitting Diode) light sources, and the moving part consists of twin area array CCDs (ChargeCoupled Device) which are symmetrically installed on and synchronously moved with the measured object. When the measured object moves, the spots projecting on twin area array CCDs will have corresponding position change, according to the change, the 3-D translational variation of the measured object can be calculated. Due to the measurement principle of translational motion in Y direction works in the same way as in X direction, the experimental system is set up to simulate and measure the 2-D translational motion in X and Z direction. Experimental results show that in comparison with HP5529A dual-frequency laser interferometer system, the measurement accuracy is better than ±1μm. The system has the advantages of high accuracy, non-contact and simple structure.