Process method for synthesizing isoprene

The invention relates to a process method for synthesizing isoprene. The process method is characterized by comprising the following steps: completely dissolving triformol in tertbutyl alcohol for measuring, and feeding the measured mixture into a synthesis reactor as a first material; feeding isobutene into the synthesis reactor for a Prins reaction as a second material; feeding a C5 enol-contained mixed solution obtained from the outlet of the synthesis reactor into a stripping tower for gas-liquid separation, obtaining unreacted isobutene at the top outlet of a gas-liquid separator, and obtaining rich-C5 methanol mixed solution from the bottom outlet of the gas-liquid separator; feeding the rich-C5 methanol mixed solution into a resolving reaction vessel, and performing a dehydration reaction under the catalytic action of Al2O3 to generate an isoprene mixture; pouring the isoprene mixture into a phase splitter, separating sewage from the isoprene mixture, inducing the isoprene mixture to a rectification column, and obtaining isoprene at the top outlet of the rectification column and by-products at the bottom outlet of the rectification column.