The invention discloses a lithium battery internal resistance measurement method. The method comprises steps: the resistance of foil in a lithium battery is acquired according to a differential model;according to the resistance of the pole piece material and the resistance of an electrolyte in a pole piece gap, the resistance of the pole piece in the lithium battery is acquired; the resistance ofa diaphragm of the lithium battery is acquired; the resistance of the electrolyte in the lithium battery is acquired; and according to the resistance of the foil, the resistance of the pole piece, the resistance of the diaphragm and the resistance of the electrolyte, the total resistance of the lithium battery is calculated, and thus, the internal resistance of the lithium battery is obtained. The invention also provides a lithium battery internal resistance measurement device. According to the above lithium battery internal resistance measurement method and the device, through acquiring theinformation of each parameter of the lithium battery and acquiring the resistance of the foil of the lithium battery, the resistance of the pole piece, the resistance of the diaphragm and the resistance of the electrolyte according to the information of each parameter and calculating the total resistance of the lithium battery, the shortcomings of long manufacturing cycle and high cost caused whena special battery internal resistance testing instrument for testing can be reduced.