The invention belongs to the technical field of powder material and particularly relates to superfine copper powder prepared through a liquid-phase ball mill reduction method and a preparation method of the superfine copper powder. The preparation method comprises the following steps: reductant is added in slurry of copper oxide powder, and grinding dispersion or ultrasonic dispersion is performed while liquid-phase reduction reaction is performed to obtain superfine copper powder; and the obtained product is filtered and dried to obtain superfine copper powder with the particle size of about 0.1 to 2 um. The preparation method provided by the invention has the advantages that raw materials are cheap, the technical process is simple, the reaction is moderate, the operation is simple and convenient, and large-scale production can be realized easily; and meanwhile, the prepared copper powder is very small in particle size and is easy to control and good in dispersity.