The invention relates to a rectifying and spray-freezing drying method for preparing polyethylene oligomer powder. The method comprises the following steps: (1) performing indirect heat exchange between a polyethylene wax solution and saturated steam, thereby separating a solvent, methylbenzene, from polyethylene wax; (2) performing indirect heat exchange between the solvent, methylbenzene, and a cooling medium for cooling the solvent, methylbenzene, till the solvent, methylbenzene, is in a liquid state, and circulating part of methylbenzene in a liquid state in a rectifying tower while discharging the rest; and (3) dividing the polyethylene wax solution into two parts, heating one part with saturated steam and returning the heated part into the rectifying tower to obtain steam condensate and discharging the steam condensate, and conveying the other part into a spray-freezing tower to form vaporific polyethylene wax drops, performing heat exchange between the drops and cold nitrogen to obtain powder and nitrogen containing superfine powder, purifying the nitrogen containing superfine powder to obtain superfine powder and purified nitrogen, and performing supercharging and cooling on most of the purified nitrogen and then returning the nitrogen into the spray-freezing tower while feeding the rest into an exhaust treatment system. The rectifying and spray-freezing drying method has a simple operation process and is high in heat efficiency.