A method for tracking metal bit line coupling effect in sensing a signal received from an array cell within a memory array is disclosed. The method includes that a reference unit with a reference cell is provided, wherein the reference unit induces coupling effect. Then, the memory array and the reference unit are charged to generate a cell signal having coupling effect and a reference signal having coupling effect. Next, a sensing signal is generated from the difference of the cell signal and the reference signal, whereby the coupling effect is compensated. In the read-out operation of the present invention, because of the closeness of two adjacent metal bit lines, the coupling effect is induced in both memory array and reference unit at the same time, so that the coupling effect is compensated. Therefore, precise read-out operation of data stored in a memory cell is made possible, and the reliability of the device is improved by the present invention.