Closed-loop test system of liquid floated accelerometer and test method of test system

The invention discloses a closed-loop test system of a liquid floated accelerometer. The system comprises an installation tool of the liquid floated accelerometer, a program control current distance adder and a dynamic simulator, wherein the installation tool of the liquid floated accelerometer distributes the gravitational acceleration on three measuring shafts equivalently, the dynamic simulator dynamically generates the acceleration under an inertia coordinate system of an aircraft, and converts the accelerometion into a liquid floated accelerometer measuring system, and the program control current distance adder applies an excitation current to a self-detection coil of the liquid floated accelerometer according to the relation between calibrated distance adding current and the acceleration, and compensate the components of the gravitational acceleration on the three measuring shafts simultaneously. A spaceborne computer collects the acceleration value output by the liquid floated accelerometer, solves the attitude and orbit control instruction, and outputs the instruction to a collection controller; the collection controller transmits the collected attitude and orbit control instruction to the dynamic simulator for solution in the next period; and thus, closed-loop test is formed.