The invention belongs to the field of 
fluorine chemical industry and specifically relates to a method for 
cracking hexafluoropropylene dipolymer to prepare perfluoro 
amyl ether and perfluoro 
amyl ether. The preparation method comprises the steps: 1) perfluoro pentacarbonyl 
ketone preparation: 1.1) sending the 
hexafluoropropylene dipolymer into an oxidizing furnace to perform 
cracking reaction withoxygen under the first catalyst condition; separating a cracked product to obtain perfluoro acetylfluoride; 1.2) preparing the perfluoro pentacarbonyl 
ketone under the second catalyst action with 
hexafluoropropylene and the perfluoro acetylfluoride prepared in the step 1.1) as raw materials; 2) selectively adding 
tertiary amine or a 
phase transfer catalyst into an 
inert dipole non-
proton organiccompound solution to react under the 
alkali metal fluoride action with the pentacarbonyl 
ketone obtained in the step 1) and an 
alkylation reagent as the raw materials, so as to prepare the perfluoro 
amyl ether. According to the method disclosed by the invention, hexafluoropropylene tripolymer is utilized as a 
raw material to generate the perfluoro pentacarbonyl ketone, and then the perfluoro pentacarbonyl ketone reacts with the 
alkylation reagent to generate the perfluoro amyl 
ether; thus, the conversion efficiency is high, conditions are moderate, and the whole technological process is simpleto operate.