In this paper, we solve the problem of experimental determination of the accuracy of a device for measuring mass-centering and inertial characteristics of nanosatellites which was developed at Samara University and based on the principle of inverted torsional pendulum. A procedure for determining the measurement error of the inertia tensor components and the center-of-mass coordinates using reference objects is proposed. For this purpose, a reference composite object of variable configuration was developed and produced in the form of a CubeSat 3U nanosatellite. With the help of this standard, a modified method of conducting an experiment was developed, which allows reducing the influence of errors in the manufacture of the device and its tooling on the measurement accuracy by averaging the homogeneous quantities. The article presents the results of a series of experiments to determine the errors in measuring mass-centering and inertial characteristics of a reference composite object of three variants of assembly. This series of experiments confirmed the measurement error theoretically calculated and stated in the technical documentation for the device. In addition, the accuracy of the electronic optical sensor installed on the device was evaluated and it was found that the influence of environmental factors on its operation is insignificant and can be neglected. The results of this work can be used to determine the error of measuring the center-of-mass coordinates and the inertia tensor components of a CubeSat 1U-3U nanosatellite at the pre-launch testing stage.