The invention provides a method for eliminating null shift effect of a sensor in a barycentric test system, comprising the following steps of: 1) measuring and recording tooling mass data before a satellite is hoisted on a barycentric table; 2) recording the data of each sensor at every moment in a whole journey in the whole satellite filling test process; 3) measuring and recording output code value of the sensor after the satellite filling is finished before the satellite is hoisted away from a barycentric measuring table; 4) measuring and recording the output code value of the sensor againafter the satellite is hoisted away from the barycentric table; 5) comparing the tooling test data before and after the satellite filling, wherein the data reflects the total null shift of the sensorin the satellite filling process; and correcting the satellite mass and barycentric measurement data according to a comparison result, and obtaining accurate results on satellite mass and barycenter.In the method, a new test process is adopted for the state after the satellite filling, namely a satellite-first tooling-second method; therefore, the test data of the satellite and tooling are the latest-measured results after satellite filling is carried out, so as to eliminate accumulated error brought by null drift of the sensor.