A method for disassembling and separating a waste lithium-ion battery comprises: directly tearing a battery pack or a cell of the waste lithium-ion battery with water and electricity without discharging after removing a housing, then performing first wet screening, directly performing wet degumming without drying after recovering an electrolyte and removing iron by magnetic separation, then performing first crushing with water, third wet screening and second crushing with water after performing second wet screening, and finally performing jigging separation to obtain copper powder, aluminum powder, positive and negative electrode materials, plastic powder and separator pulp.