The invention discloses a method for recovering and extracting four metal elements including cobalt, copper, aluminum and lithium in a waste lithium ion battery by using liquid phase reaction. The method comprises the following steps: (1), dispersing 1-1000 g of mechanically crushed waste battery powder in a sodium hydroxide solution, after completely dissolving a dissoluble part in the battery powder, separating plastic powder and carbon powder from an upper layer of the solution and separating electrode powder in a lower layer of the solution by using a cyclone separation method, and obtaining copper powder from a filter net at a middle layer of the solution; (2), obtaining aluminum hydroxide sediment; (3), obtaining lithium carbonate sediment; and (4), obtaining cobalt oxalate. According to the method, the separation of cobalt, copper, aluminum and lithium is realized, aluminum hydroxide, cobalt oxalate and lithium carbonate prepared by using the method are uniform and consistent, and high in degree of crystallinity; and aluminum hydroxide, copper powder, cobalt oxalate and lithium carbonate are obtained, therefore, recycling of a battery material is realized, the cost is low, and the method is suitable for large-scale industrialized production.