The invention relates to a liquid-injection process of a low-temperature lithium ion battery cell. The liquid-injection process is characterized by comprising the following two steps: (1) when a liquid is injected into the lithium ion battery cell, firstly injecting an electrolyte capable of forming a good SEI (solid electrolyte interface) film, sealing and standing, thus forming the cell; (2) after forming the cell, injecting the rest of the other low-temperature electrolyte or low-melting point solvent, and sealing. The process can be used for solving the use problems of solvents of PC (polycarbonate) and linear carboxylic ester which are in favor of improving the battery low-temperature performance and are bad for the formation of the SEI film, therefore, the battery low-temperature performance is improved; and meanwhile, the gas generated at the early charge process of the battery when an electrode forms the SEI film can be removed.