Abstract: J-T valve+ethylene glycol low temperature freezing separating process was adopted to separate water and hydrocarbon of natural gas, and prevent hydrate formation by ethylene glycol in Dina 2 gas field. The design capacity of a single set is 400×10⁴ m³/d and the design refrigeration temperature is -20 ℃. When the plant started production, the feed gas temperature raised from 45 ℃ to 65 ℃. The ethylene glycol dosage was too small to prevent the hydrate formation under the design refrigeration temperature, and the hydrate formed in the LT separator frequently. The process capacity was restricted to 200×10⁴ m³/d, and the refrigeration temperature was -15 ℃. In this paper, the simulation and optimization of the dehydration and dealkylation unit was studied by HYSYS software. The increasing saturated water of feed gas resulted in the hydrate formation. The appropriate parameters table was set out, which helped to prevent hydrate formation. The process capacity of dehydration unit meets the requirement of design parameter after the installation of water separator. The yield of LPG and light hydrocarbon are improved significantly while the loss of ethylene glycol was decreased. The standard gas process was proposed for condensate gas, which flow into air cooler first then by water separator.