The invention discloses a preparation method of a component volatile deep degassed solution. The prepared solution of certain concentration includes n solutes, and the steps comprise: subjecting a solvent container to vacuum pumping, sealing and weighing, and denoting the mass of the solvent container as m1; adding a solvent into the solvent container, conducting sealing and refrigeration, when the solvent is all frozen, subjecting the solvent container to vacuum pumping, sealing and weighing, and denoting the mass of the solvent container as m1'; calculating the mass of each solute; subjecting the solvent container to vacuum pumping, sealing and weighing, and denoting the mass of the solvent container as m2; adding an i-th solute with a mass of m solute i into the solvent container, then conducting vacuum pumping, sealing and weighing to obtain total mass m2i; adding the 1st solute till the n-th solute into liquid one by one until all the solutes are fully dissolved; and calculating the exact concentration of each solute in the prepared solution of certain concentration. The invention also discloses a vapor pressure determination method of the component volatile deep degassed solution. The method provided by the invention avoids the problem of difficult accurate determination of the solution concentration after a conventional degassing process, and greatly improves the measurement accuracy.