A novel method for preparing high-temperature resistant low-sodium aluminum hydroxide is disclosed. The method includes slowly adding an inorganic acid solution dropwise into a sodium aluminate solution having a temperature of 80-90 DEG C; 1-3 min after addition of the inorganic acid solution, starting ultrasonic treatment until 0.5-1 h after the end of precipitation; and performing filtration andwashing on the precipitate to obtain aluminum hydroxide solid, wherein the frequency of ultrasound waves is 20-60 kHz. The method avoids agglomeration, reduces the content of sodium oxide encapsulated during precipitation, and satisfies the requirements for the particle size and sodium content of aluminum hydroxide under different conditions. The method effectively solves the problem that the particle size distribution is uneven and the sodium content cannot be reduced in the traditional processes, and the method is simple in process, low in equipment requirement, relatively low in cost, freeof generation of three wastes and suitable for large-scale industrial production.