A light-emitting module and a driving method thereof are disclosed. In this method, P light-emitting units are selected as a target group, wherein each of the P light-emitting units has N different power parameters corresponding to N sub-bands. P evaluated current values corresponding to the P light-emitting units are computed according to a target spectrum and the N×P power parameters corresponding to the P light-emitting unit in the target group. An emission-spectrum error is computed according to the target spectrum, the N×P power parameters, and the P evaluated current values. It is determined whether the emission-spectrum error conforms with the determining criteria. When the emission-spectrum error conforms with determining criteria, the P evaluated current values are set to be P driving current values corresponding to the P light-emitting units.