The invention relates to a method for utilizing alkaline etching waste liquid in a printed circuit board to prepare nano-copper which is made into nano-copper conductive slurry. The method comprises the following steps: filtering alkaline etching waste liquid, adding a nonionic surfactant of 0.43%-4.24% of alkaline etching waste liquid by weight and an aqueous antifoaming agent of 0.08%-1.61% of the alkaline etching waste liquid by weight, preparing a reaction solution A; preparing a reducing agent solution B which comprises a reducing agent of 1.70%-8.49% of the alkaline etching waste liquidby weight, a highly basic substance of 6.80%-10.20 % of the alkaline etching waste liquid by weight, and organic phase turpentine which is used for a phase-transfer agent and has a volume ratio of 1:1-1:2 to the alkaline etching waste liquid; carrying out heating and stirring, and adding the reaction solution A in to the reducing agent solution B drop by drop. The method has the characteristics of easy operation and small energy consumption, prepared nano-copper powder has good antioxidation performance, by utilizing the etching waste liquid, conductive slurry of a high added value is prepared, a high economic benefit is created, emission reduction and no pollution of waste water are realized, and resource recycling is achieved.