To modify the mechanic properties of high water backfill material (HWBM) for its engineering application in mining backfill, a series of experiments were performed to investigate the effects of electrochemical treatment on the mechanic properties and electrical resistivity of the HWBM at the early age. Meanwhile, the effects of the potential gradient, power-on time, and water–cement ratio (W/C) on electrochemical modification efficiency were investigated. The results show that the uniaxial compression strength (UCS), elastic modulus, and deformation modulus of the HWBM all first increased and then decreased after electrochemical treatment with the increasing of the potential gradient and power-on time. However, for the HWBM with different W/C, the UCS and electrical resistivity both increased the HWBM except when the W/C was 3 : 1. The elastic modulus and deformation modulus of the samples both increased after electrochemical modification except when the W/C was 4 : 1. Additionally, there is a positive correlation between the UCS and electrical resistivity in HWBM samples. Therefore, it is proved that the electrochemical technology is a potential method for improving the physicochemical properties of the HWBM.