Abstract: In order to optimize SRAP-PCR reaction system for Chinese fir,the orthogonal design L₁₆(4⁵)was considered with different concentrations of Mg²⁺, dNTPs, primer, Taq DNA polymerase and DNA template in SRAP-PCR reaction system for Chinese fir. The results of PCR were evaluated by visual and variance analysis,then the concentrations of Mg²⁺,dNTPs,primer were rectified with single-factor design. Finally,the results showed that the best reaction system was the combination in 20 μL reaction solution,containing of Mg²⁺ 2.25 mmol/L,dNTPs 0.15 mmol/L,primer 0.4 μmol/L,Taq DNA polymerase1.5 μmol/min and DNA template 60 ng,2 μL10×PCR Buffer and ddH₂O to 20 μL. The first optimal annealing temperature was 35 ℃,and the second step was 53 ℃. The optimized reaction system of Chinese fir described above can get clear and stable bands.