Methods of calculating a compensation voltage and adjusting a threshold voltage, a memory apparatus, and a controller are provided. In the present invention, data is written into a rewritable non-volatility memory, and the data is then read from the rewritable non-volatility memory and compared with the previously written data to obtain error bit information. The compensation voltage of the threshold voltage is calculated according to the error bit information, and the threshold voltage is adjusted according to the compensation voltage.