The invention relates to a method for preventing a low-temperature methanol washing heat regeneration system from being corroded. The method is characterized by comprising the following steps: enabling crude synthetic gas from the upstream to enter a conveying pipeline; after detecting the content of HCN (Hydrogen Cyanide) in the crude synthetic gas through an HCN detector in real time, conveying the crude synthetic gas into a raw material cooler I; after cooling, separating out condensed liquid and mixing the condensed liquid with circulating gas; spraying a first stream of anti-freezing methanol and then cooling; then enabling the gas to enter a synthetic gas HCN washer and washing by CO2-enriched methanol; enabling the washed gas to enter a washing tower, and sequentially washing to obtain H2S and CO2 in a synthetic gas rising process; pumping out the generated CO2-enriched methanol and H2S-enriched methanol and conveying the same into a middle-pressure flashing tower respectively to recycle the crude synthetic gas; then conveying the crude synthetic gas into an H2S concentration tower for carrying out gas stripping; enabling the H2S-enriched methanol to enter a heat regeneration tower for regeneration; after discharging regenerated lean methanol from the bottom of the heat regeneration tower, dividing the regenerated lean methanol into two streams, wherein the first stream is used as the anti-freezing methanol and the second stream is conveyed into the washing tower; after carrying out heat exchange on HCN-enriched methanol, enabling the HCN-enriched methanol to enter a CO2 flashing tower for carrying out flashing.