The method for a hydrocarbon mixture composition determination includes the collection of at least one sample of the hydrocarbon mixture. For this sample, a nuclear magnetic resonance method is used for measuring series of hydrocarbon mixture's free inductance decrement curves within a temperature range of −150° C. to +150°. Each free inductance decrement curve is then used to determine the solid component fraction Ps in the NMR 1H signal at a temperature, at which this value was measured. The received values are then used to plot a temperature dependence of the solid component fraction Ps in the NMR 1H signal and, based on the Ps value variation (ΔPsi), caused by a phase transition of the ith component due to a heating or cooling process and the content of solid and/or liquid phase components in the hydrocarbon mixture is defined by attributing the ΔPsi value to the associated components of the mixture.