The present invention relates to a new process for preparing optical pure tetrahydrofuran-2-formic acid. Said process includes the following steps: adopting a configurational tartaric acid derivative O,O'-diarylformacyl tartaric acid to resolve tetrahydrofuran-2-formic acid; making reaction produce undergo the processes of crystallization, and recrystallization to obtain a configrated optical pure tetrahydrofuran-2-formic acid, then making another isomer in mother liquor of the above-mentioned crystallization operation and achiral amine form salt and undergo the processes of crystallization and recrystallization so as to make its optical purity be up to 89-99% e.e. heating another configurated isomer whose optical purity is less than 98% e,e in the mother liquor of the above-mentioned crystallization operation under the alkaline condition to make racemization to produce racemic body, repeatedly making resolution and above-mentioned steps so as to obtain two kinds of configurated optical pure tetrahydrofuran-2-formic acid.