Abstract: Osmotic coefficient (ϕ) is a measure of the deviation of the solvent of electrolyte from the ideal solution. ϕ was usually determined by the manometric method and the electromotive force method. National bureau of standard of United States of America published the reference value of osmotic coefficient equal to the average of many scientific data and its standard deviation based on the statistics. This reference data was expressed as the Debye-Hückel equation. When the molality of the electrolyte was introduced in the equation, and thus the corresponding osmotic coefficient was deduced. ϕ can be used to calculate the water activity, freezing point depression and osmotic pressure concentration of the solution of electrolyte, and thus the reference solution of these quantities were determined and then used to calibrate the instrument of these quantities. Sodium chloride was the most commonly used electrolyte. The reference values specified by the related international or national standard were well consistent with the results calculated using the reference data of ϕ. The reference values of related physical chemistry quantities calculated using the reference data of ϕ were traceable to SI units of vapor pressure or potential of the electromotive force indirectly.