In the production of low temperature coal to methanol by copper catalysis, the formed paraffin can easily lead to the blockage of the final cooler and separator, thus influencing the production of methanol. The reasons of paraffin formation in methanol synthesis and the prevention and treatment measures were discussed. It is put forward by controlling the water vapor in the feed gas and the reaction temperature in the range of 210 ~ 260 ℃, reducing  the loop pressure in synthesis system and improving airspeed, the paraffin precipitation can be reduced. And Low pressure steam is used to heat the final cooler  to removetheparaffin precipitation.