Abstract: A practical method is established for determining the radiochemical purity of ~(18)FDG rapidly. It offers three systems to separate ~(18)FDG and ~(18)F~-. The stationary phase of these are ITLC/SG? Whatman No.1 and silica paper, their corresponding mobile phase are V(acetionitril)∶V(water)=95∶5, V(methanol)∶V(water)=9∶1 and methanol, respectively. Twelve batchs of()~(18)FDG are determined, its radiochemical purity is more than 96%. The precision is less than 1%.