The invention discloses a preparation method of a zinc telluride single crystal, and aims to solve the technical problem that the zinc telluride single crystal prepared through the existing method is low in quality. The technical scheme is that the preparation method comprises the following steps: putting a high-purity tellurium elementary substance and a synthesized zinc telluride polycrystal raw material into a quartz crucible for fused sealing under high vacuum; then putting the quartz crucible into an ACRT (Accelerated Crucible Rotation Technique) type five-temperature-region crystal growth furnace; firstly, heating the furnace at a certain heating rate, thus obtaining a preset temperature field, preserving the heat for a period of time, and cooling the crucible at a rate of 0.1 to 0.2 mm/h, wherein the temperature gradient for crystal growth is 10 +/- 1 DEG C/cm and the crystallizing temperature is 1,060 +/- 1 DEG C; and under a condition of keeping the temperature field in a growth process unchanged, after the crystal grows, cooling the crucible at 3 DEG C/h for 50 hours, then cooling the crucible at the rate of 5 DEG C/h for 100 hours, and finally turning off a power supply for furnace cooling. According to the preparation method, the ZnTe crystal with an enough length and high crystallizing quality is obtained.