A reading control method for a solid state storage device includes following steps. If a hard decoding process fails, a first histogram parameter and a second histogram parameter are generated in the hard decoding process according to a first sensing voltage, a second sensing voltage and a third sensing voltage. Then, a voltage shift amount is obtained according to the first histogram parameter, the second histogram parameter and a voltage shift function. The first sensing voltage, the second sensing voltage and the third sensing voltage are updated according to the voltage shift amount. Then, a soft decoding process is performed. The updated first sensing voltage, the updated second sensing voltage and the updated third sensing voltage are provided to a non-volatile memory, so that the non-volatile memory generates a soft data.