A testing program of researching on the impact on the change of capacitor capacity value of harmonic amplitude and phase, the size of the fundamental wave and the voltage RMS, peak and waveform factors which reflect the characters of the harmonic and fundamental wave in 10kV is made in this paper. And the study of relevance between harmonic and change of capacitor capacity value has been carried on. On the basis of experimental study, this paper quantitatively analyzed the relationship in detail between the change of capacity value and the harmonic amplitude and phase, the size of fundamental wave and the three factors which reflect the characters of the fundamental and harmonic wave before and after the test, and then a qualitative relationship between the change of capacitor capacity value and the three factors is given.