The invention discloses a method and device for preventing ammonia and organic sulfur accumulation in a low temperature methanol washing system and removing device ammonium bicarbonate crystals, and belongs to the technical field of organic chemical engineering. The adopted technological method includes the steps of using a small amount of heat regeneration tower backflow liquid rich in organic sulfur as spraying methanol of a sulfuretted hydrogen enrichment condenser, conducting extraction after separation, conducting recovering through an extractive distillation column, making condensate on the top of the extractive distillation column enter an extractor to separate btx aromatics from methanol, and using a methanol-water mixture as backflow of the extractive distillation column. An extractor water cooler and bath tower scrubbing solution alkali adding liquor are adopted; by means of the least amount of methanol, the ammonia and organic sulfur accumulation of the system is solved, no overlarge burdens can be caused to a pre-washing methanol regeneration system, the device ammonium bicarbonate crystal problem is solved, the temperature in the extractor is adjusted, and it is avoided that the extraction and separation effect is influenced by excessive temperature; due to the bath tower scrubbing solution alkali adding liquor, the device corrosion of the pre-washing regeneration system is avoided, and meanwhile ammonia can be easily removed.