The invention relates to a cell preassembling device. The cell preassembling device includes a machine platform, a cell conveying line, an interval-adjustable negative pressure adsorption disc, a material ejecting and pushing mechanism, a turn-over clamping mechanism and a lower support fixing mechanism; a first sliding rail, a second sliding rail and a third sliding rail are arranged on the machine platform; the turn-over clamping mechanism includes a material moving sliding device, a connection arm, a turn-over adsorption device and a turn-over motor. According to the cell preassembling device, the material ejecting and pushing mechanism and the turn-over clamping mechanism are adopted, a cell is turned 90 degrees and then placed into a lower support, occupied labor is reduced, the assembly efficiency is improved, and human errors are avoided.