Abstract: An electric hydraulic floor jack includes a variable plunger structure provided on a motor base and an oil pump base. The variable plunger structure includes a piston hole formed in the oil pump base and communicating with an oil chamber and an oil inlet passage, a plunger sleeve provided at a port of the piston hole, a plunger slidably provided in the plunger sleeve, a U-shaped piston slidably provided in the piston hole, a valve trim slidably provided on the piston, a spring provided in the piston hole and sleeved on the valve trim, and an eccentric wheel provided on an output shaft of a speed reducer. The plunger is driven by the eccentric wheel in cooperation with the spring to continuously make a linear reciprocating motion, thereby continuously opening and closing the check valve, and pumping oil into the cylinder to push the piston rod for lifting work.