The invention relates to a sodium vanadate crystallization system and a sodium vanadate crystallization method. The system comprises a buffer tank, a heat exchange tank, a crystallizer, a thickener, a crystal slurry storage tank, a filter press and a mother solution tank which are sequentially arranged, wherein the mother solution tank is connected with a supernate discharging hole of the thickener. According to the system, a sodium vanadate solution stored in the buffer tank is conveyed into the heat exchanger, is cooled and is conveyed into the crystallizer to be crystallized and separated, crystal slurry at the bottom of the crystallizer is conveyed into the thickener to be thickened, supernate is stored into the mother solution tank, the thickened crystal slurry is conveyed into the crystal slurry storage tank and is separated into sodium vanadate crystals and separation liquid by virtue of the filter press, and meanwhile, the separation liquid is stored into the mother solution tank. According to the method, the particle size and moisture of the sodium vanadate crystals can be effectively controlled, the problem of blockage of the sodium vanadate crystals is solved, the efficiency of the crystallization system is improved, the crystallization control of the sodium vanadate solution is realized under a high-alkali condition, and the stable and efficient operation of the crystallization system are guaranteed; and the method has good application prospects.