Abstract: The electrical conductivity of the molten salts of KNO3-NaNO2-NaNO3 ternary system with different compositions was measured at different temperatures by the continuously varying cell constant (CVCC) technique. The main influencing factor on electrical conductivity was analyzed. Experimental results showed that the electrical conductivity measured by CVCC technique is accurate and reliable, of which the relative error is just 0.78% in comparison with what was given by the reference [9]. There is an exponential relationship between the conductivity and reciprocal value of temperature in the system, and the conductivities of the melts are variable because they are affected by the different compositions of the system. With the increasing content of NaNO2, the electrical conductivity of this system increases, while it decreases with increasing content of KNO3. As to the content of NaNO3, it affects little the conductivity.