A preparation method for a trans-cyclobutane-o-dicarboxylic acid ester and a derivative thereof includes the following steps: in an organic solvent, catalyzing a substrate with a structure as shown in a structural formula I by using organic alkali at 50-90 C. so as to generate isomerization, acquiring the trans-cyclobutane-o-dicarboxylic acid ester or the derivative thereof, herein the structural formula I is as follows: ##STR00001##
Each R.sup.1, R.sup.2, R.sup.3 and R.sup.4 is independently one of hydrogen or an alkyl of C.sub.1-C.sub.5, and each of R.sup.5 and R.sup.6 is independently one of alkyl of C.sub.1-C.sub.10 and benzyl.