The invention relates to a TDS (Total Dissolved Solid) detection method and device and belongs to the field of communication. The method comprises the following steps: setting first alternating voltage and second alternating voltage, wherein in the same alternating period, a high electrical level time period of the first alternating voltage and a high electrical level time period of the second alternating voltage have no overlapping; and when a TDS detection probe is used for carrying out TDS detection in a water path to be detected, applying the first alternating voltage and the second alternating voltage to two electrodes of the TDS detection probe respectively to carry out the TDS detection. The device comprises a first setting module and a triggering module. According to the TDS detection method and device provided by the invention, the two electrodes of the TDS detection probe can be effectively prevented from a polarization phenomenon by the alternating voltage so that the probe can stably and reliably work for a long period, errors are reduced and the TDS detection accuracy is improved.