The invention belongs to the field of new materials and semiconductors and particularly relates to a low-temperature liquid phase preparation method of a hafnium oxide dielectric film. The method comprises the following steps of weighing a soluble hafnium salt, measuring a solvent, preparing a hafnium oxide precursor solution of which the concentration is 0.01-0.5mol/L and forming the clear and transparent hafnium oxide precursor solution through magnetic stirring and ultrasonic dispersion for 0.1-3 hours; and preparing a hafnium oxide film, coating a cleaned substrate with the hafnium oxide precursor solution to form a hafnium oxide precursor film, carrying out preheating treatment of 50-150 DEG C and carrying out multiple coating of the hafnium oxide precursor solution and annealing treatment through light wave annealing of certain power, time and temperature according to the thickness requirement of the hafnium oxide film, thereby obtaining the hafnium oxide dielectric film. The obtained hafnium oxide dielectric film is high in dielectric property and has an important application prospect in the field of microelectronics of a transistor, a capacitor and the like. Through the technology provided by the invention, a common high-temperature solution technology, a long process cycle or expensive equipment and the like can be avoided, the cost is low and the low-temperature liquid phase preparation method is suitable for industrialized mass production.