Provided are a recombinant strain for preparing a terpenoid, and method for constructing the recombinant strain. Also provided is a recombinant bacterium 1, the recombinant bacterium 1 being a recombinant bacterium obtained in order to improve the enzymatic activity of α-ketoglutarate dehydrogenase in escherichia coli or the mutant thereof. The method for improving the enzymatic activity of α-ketoglutarate dehydrogenase in escherichia coli or the mutant thereof is replacing the original regulating element of the ketoglutarate dehydrogenase gene (sucAB) in escherichia coli or the mutant thereof with any of the following regulating elements: artificial regulating element M 1-46, M1-37, and M1-93. Also provided are a plurality of recombinant bacteria. By improving the enzymatic activity of α-ketoglutarate dehydrogenase, succinic acid dehydrogenase and transaldolase therein and improving the ability of a cell to synthesize NADPH and ATP, the efficiency of the MEP pathway and the production capacity of terpenoid are improved.