The invention provides a preparation method and a preparation device of copper powder. The preparation method comprises the following steps of (S1) preparing a copper powder suspension, wherein the boiling point of a liquid medium of the copper powder suspension is below 100 DEG C; (S2) enabling the copper powder suspension to flow through a rotary centrifugal atomizing disc, so that droplets of the suspension are cut into fine suspension droplets under the centrifugal action of the centrifugal atomizing disc, heat is transferred to the fine suspension droplets by hot air in the process that the fine suspension droplets centrifugally fly out, the liquid medium of the copper powder suspension is evaporated, solid-liquid separation is realized, and solid powder is collected so as to obtain the copper powder. By adopting the technical scheme of the preparation method, the problem of powder aggregation in a conventional vacuum drying method is solved, and the subsequent procedures are reduced; additionally, for boron modified powder for conductive copper slurry, an anti-oxidation effect can be achieved in a drying process, and the requirement that inert gas shielding is needed in a sintering process of modified copper powder is reduced.