The Sun is a giant natural nuclear fusion reactor. For the Sun to shine with the present luminosity, its hot plasma core needs to fuse protons in a rate of one part per billion-billions into helium nuclei in one second. Fusing all of the core's protons, the Sun can glow at the present brightness for around ten billion years. In accordance with the Maxwell-Boltzmann distribution, the core's 1.5-keV temperature is too low for any pair of protons to be able to overcome the 820-keV Coulomb barrier and fuse them into a deuteron. It is generally believed that the quantum tunnelling effect plays the key role in the solar nuclear fusion reactions. Since the Gamow peak is only at the energy of about 7 keV, much lower than the barrier, the tunnelling probability is extremely enhanced to be one part per million. With this probability of barrier penetration, the high ion collision rate leads to the Sun to fuse its all protons within just one tenth of microseconds and hence to instantaneously explode. The solar strong gravity and diproton rare β+-decay may not be sufficient enough to reduce the fusion rate by twenty-fifth orders of magnitude. For not occurrence of this instantaneous explosion, the core of the Sun probably possesses another extremely significant physical mechanism to inhibit its high rate of nuclear fusion. In this study, we found that a high-frequency plasma oscillation can be this efficient inhibitor, because it significantly reduces the electric permittivity of the core plasma and hence extremely raises the Coulomb barrier and shifts the Gamow peak to a higher energy. Quantitative study indicates that if the Langmuir waves are generated in the turbulences of the core plasma and wave frequency is about one-third higher than the plasma frequency or the wavelength is about the diameter of the Debye sphere, the Sun can have the actual fusion rate and the observed luminosity. Therefore, in addition to the quantum tunnelling effect and diproton's β+-decay rareness, the plasma oscillation can also play an important role in the Sun's nuclear fusion and power emission. This result has also an important implication not only to astrophysics such as solar neutrino missing but also to plasma fusion in laboratory.