HFO-1234yf, as an alternative to traditional refrigerants and halon fire extinguishing agents, is environmentally friendly and low toxic. In this study, the corrosion behavior of HFO-1234yf to magnesium alloy materials was studied at high temperature. The result shows HFO-1234yf without pyrolysis is compatible with AZ80A alloy and has no corrosive effect on AZ80A alloy. The HFO-1234yf pyrolyzed at 400 °C to produce C4 products and HF. The corrosion of the alloy surface by HF caused the formation of MgF2, which caused increased mass and decreased ultimate tensile strength of AZ80A.On this basis, corrosion products and gaseous products were further analyzed, and the corrosion mechanism of HFO-1234yf on magnesium alloy at high temperature was explained. The results are helpful for the safe application of HFO-1234yf and screening of Halon substitute agents.