Single factor test of concentration of dNTP, Mg²⁺, Taq DNA polymerase, primer and DNA template was used to optimize the ISSR-PCR amplification system which has been established initially. The results showed that suitable ISSR-PCR reaction system for Odontotermes formosanus was 20 μl reaction system containing 2.5 U Taq DNA polymerase, 2.0 mmol·L^-1 Mg²⁺, 0.1 mmol·L^-1 dNTP, 1.0 μmol·L^-1 primer and 20 ng DNA template.