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.