Molybdenum disulfide (MoS2), as a kind of 2D material with novel physical properties and excellent electrical performance, has great application potential in the field of electronic devices. Efficient and controllable growth of large-size single crystal MoS2 is a major difficulty that must be overcome towards scalable production. Chemical vapor deposition (CVD) is considered as the most promising means for industrial production of 2D materials. Herein, we report the growth of high-quality and millimeter-level single crystals MoS2 on molten glass by pre-deposited CVD method in which MoO3 film deposited on the glass is used as Mo precursor instead of MoO3 powder. In addition, by introducing WO3 powder into such CVD system, MoS2-WS2 lateral heterojunctions can also be obtained. Raman and PL measurements indicate that the as-grown MoS2 monolayer samples possess high quality. Back-gate FETs were fabricated on SiO2/Si substrates by using transferring elelctrode methods to investigate the electrical properties of the as-grown MoS2 crystals. At room temperature and atmosphere pressure, the on-off ratio can reach 105 and the carrie mobility can reach 4.53 cm2V-1s-1. The low-cost and high-quality large-size material growth method pave a way for scalable production of such 2D material based electronic devices.