By using canonical transformation,the quantization scheme of mesoscopic RLC circuit is given. With the aid of numerical calculation,the regulation is investigated about how the Wigner function of the thermal vacuum state varies with the temperature. Meanwhile,the quantum effects of the charge and self-conductance magnetic flux in the thermal vacuum state are discussed by using Weyl-Wigner correspondence. It is found that,Wigner function of the thermal vacuum state at low temperature is a stable wave packet,but it diffuses with the temperature increasing and the quantum effects of charge and self-conductance magnetic flux in the thermal vacuum state vary with the temperature and time,besides the circuit parameters.