Abstract: Genomic DNA of Radish was analyzed by optimizing the concentration of Mg²⁺, dNTPs and primer in Random Amplified Microsatellite Polymorphism (RAMP) system. Three different concentration gradients were set respectively, Mg²⁺ 0.75，1.5，3.0 mmol·L^-1；dNTPs 0.05，0.15，0.3 mmol·L^-1；primer 0.065，0.2，0.4 μmol·L^-1, and the suitable annealing temperature was also screened. An optimization of RAMP reaction system for radish genomic DNA is（20 μL）: dNTPs 0.15 mmol·L^-1，Mg²⁺ 1.5 mmol·L^-1，primer 0.2～0.4 μmol·L^-1，DNA 10 ng，Taq E 0.8U.The amplification protocol was: 94℃ 3 min，42 cycles for 1 min at 94℃，1 min at 45℃, 1.5 min at 72℃, followed by a final extension of 8 min at 72℃. The suitable system was applied in screening the primer combinations, and the genetic diversity of seven radish varieties was analyzed in RAMP marker system.

Key words: radish, RAMP marker, system optimization, genetic diversity