This paper presents a research on the Czochralski growth of large size YVO4 crystal with autocontrolled diameter. The large size YVO4 single crystal was successfully grown by the Czochralski process with modified up-weighing method. In the Czochralski growth process of large size YVO4 crystals, the slope integral mode was used in the shoulder expanding part, transition from slope integration to diameter integration mode was used in the shoulder turning part, and the diameter integral mode was used in the growth of the equal diameter part. The automatic growth of YVO4 crystal has been realized by the subsection controlling procedure described above. The reliability of the automatic growth process of YVO4 crystal was verified with four 50 mode automatic furnaces in a duration of one year. The technical goal of grown crystals was preset as follows: a crystal diameter of more than 40 mm, a length with the equal diameter part of more than 30 mm, and more than 80% production of B-grade quality crystals. A total of 138 crystal boules were grown by the Czochralski process with autocontrolling mode. The statistic data was summerized as 99.3% crystal boules with the standard diameter, 53.6% crystal boules with the standard length, and 88.4% yield of crystal growth. The technological factors concerning of the yield of crystal boules with the standard length of equal diameter part were also discussed.