The invention relates to a crystallization separation method for preparing high-purity o-cresol. The method comprises the following steps: adding crude o-cresol into a tubular crystallizer, controlling the temperature of the system to be 35-50 DEG C, and performing constant-temperature standing for 0-0.5 h; reducing the temperature to 26.5-29.5 DEG C within 0.5-4 h, and adding a certain amount ofseed crystals into the crystallizer 0.33-1 h later; cooling obtained crystals to 25-28.5 DEG C at a constant speed within 2-5 h, growing the crystals for 1-3 h, and discharging the obtained mother liquor; raising the temperature to 27-29.5 DEG C at a constant speed within 2-5 h for sweating, continuously growing the crystals for 0.5-2 h after the temperature is raised to the sweating operation temperature, and discharging sweat; and then rapidly raising the temperature to 35-45 DEG C to melt the solid in the crystallizer, and discharging the o-cresol product from the bottom of the crystallizer. The purity of the obtained o-cresol product is 99.50-99.99%, and the yield is greater than 75%. The method has the advantages of realization of high purity and high yield of the product, simplicityin operation, and easiness in realization of industrial production.