The invention discloses a heat shrinkage-resistant lithium ion battery diaphragm, a production method of the diaphragm, and an extractant composition used by the diaphragm. The extractant composition comprises a first extractant and a second extractant, the first extractant is a mixture comprising dichloromethane and phosphate ester, and the second extractant is water. The extractant composition provided the invention has a complete extraction effect on pore forming agents, and realizes less residual of the pore forming agents, and the battery diaphragm with good comprehensive performances can be produced from the pore forming agent, a specific pore forming agent and a specific ratio of macromolecular polyethylene and ultra-macromolecular polyethylene through a specific device by using a processing technology.