In order to establish a suitable ISSR-PCR reaction system for Parashorea chinensis this study used young leaves of Parashorea chinensis as the test material and used the L₁₆ 4⁵ orthogonal experimental design to optimise the five factors of ISSR-PCR reaction i e template DNA Mg²⁺ dNTPs Taq DNA polymerase and primer concentrations and to establish an optimal ISSR-PCR reaction system suitable for Parashorea chinensis On the basis of the optimisation the primers and the optimal annealing temperature were selected and the stability of the reaction system was verified by using five Parashorea chinensis family lines as materials The results showed that the optimal ISSR-PCR reaction system 20 μL for Parashorea chinensis was composed of 90 ng of template DNA 0 3 μmol L of primers 0 2 mmol L of dNTPs 2 5 mmol L of Mg²⁺ and 1 0 U of Taq DNA polymerase and that the three ISSR-PCR reaction systems with good reproducibility and high polymorphism were screened Three ISSR primers with good repeatability clear bands and high polymorphism were selected and the optimal annealing temperature of the best primer UBC864 was 56 9 ℃ The optimised reaction system and primers were used to detect the ISSR-PCR bands of five Parashorea chinensis samples and the results showed that the above reaction system was stable and reliable The optimized ISSR-PCR system and primer candidates are suitable for the genetic diversity analysis of Parashorea chinensis which can lay a foundation for the conservation and utilisation of Parashorea chinensis germplasm resources