A three-point method for bridge deflection estimation is proposed. Measuring points are selected along the span axis, and every three adjacent measuring points are defined as a measuring unit. In each measuring unit, the displacement of the mid-measuring point relative to the reference line linking the other two measuring points measured by the grating eddy current sensor is defined as the relative deflection. Deflections of each measuring point can thus be calculated from the relative deflections of all the measuring units directly. Both static and dynamic experiments have been carried out on a simple beam bridge model.The experimental results demonstrate this method is precise and effective. 