Abstract: The synthesis conditions of radiopharmaceutical-N-methyl-¹¹C Choline (¹¹C-Choline, ¹¹C-CH) with home-made 11Cmultifunction synthesis module by LOOP method were studied, which included the alkali equivalent, solvents and the amount of precursor. The optimum condition was 60-150 uL of precursor in LOOP without alkali equivalent and solvent, and at room temperature for synthesis of ¹¹C-CH. It could be got with radiochemical yield of (72.16±2.96)% (n=19, EOS of ¹¹C-CH₃I). The radiochemical purity of ¹¹C-CH was higher than 95% and the production radioactivity was (7.59±1.54) GBq(n=19). The synthesis of ¹¹C-CH by LOOP and on-column method on home-made ¹¹C-multifunction synthesis module was compared: by the method of LOOP, it showed that the production efficiency was increased, the output was increased and production cost of synthetic was reduced. The synthetic process was reliable and fully automatic, and the product synthesized by this process was suitable for clinical use.