Abstract: The DNA templates of Heptacodium miconioides extracted from young leaf were amplified by RAPD. Effects of the content of Mg2+, dNTP, DNA templates, primers and DNA polymerase on experimental results were tested and the optimal reaction system of RAPD for Heptacodium miconioides was determined as follows: 1×Taq polymerase corresponding buffer (10 mmol/L Tris·HCl pH 9.0，50 mmol/L KCl, 0.1% Triton X_100), 2.5 mmol/L MgCl2, 2U Taq DNA polymerase, 10 ng template DNA, 20 pmol primer, 0.1 mmol/L dATP, dCTP, dGTP, dTTP separately in total 15 μL reaction volume.