A method for improving an over erasing effect of a charge-trapping memory cell. The charge-trapping memory cell has a transistor, which has a first terminal coupled to a first bit line and a second terminal coupled to a second bit line. First, the method erases the charge-trapping memory cell. Then, after the charge-trapping memory cell is completely erased, the first bit line is electrically connected to the second bit line to make a voltage level of the first bit line equal a voltage level of the second bit line such that the voltage level of the first terminal of the transistor equals the voltage level of the second terminal of the transistor.