To study the effect of reference plane inclination on micro-thrust measurement, a high-precision ground inclination measurement method based on an inverted pendulum structure is proposed.The effect on system stiffness and measurement accuracy is explored by precisely controlling the inclination angle of the reference. Calibration experiments using a high-precision electromagnetic calibrated force revealed that the gravitational moment of the inverted pendulum was about 162.80 mNm and the initial inclination angle of the installation reference was about -1.78 mrad. Next, an experimental study on the effect of reference plane inclination is conducted by piezo deflector stage, followed by an uncertainty analysis. The experimental results indicate that the reference plane inclination has a significant amplifying of pendulum deflection angle when the pendulum gravity moment stiffness is approaching the flexible pivot stiffness.The amplification is about 5.73 when the gravitational moment is 162.80 mNm and K0=191.46 mNm/rad, which is 0.25% different from the simulation results. Due to the amplification effect of the inverted pendulum, the stiffness of the inverted pendulum will be deviated by 57% at a reference plane inclination angle of 10 μrad.The deviation of the micro-thrust measurements was better than 0.98% and the deviation of the system stiffness was better than 2% with the model correction. Considering the effects of the experimental environment and instrumentation, the relative uncertainty of the experimental measurements was 1.40%. The results of the study provide support for improving micro-thrust measurement performance.