Three (17, 20, 21) fractions of methanol extracts of Loranthus micranthus yielded different phytochemicals was confirmed by GC-MS analysis. The fraction 17 yielded 13 different phytochemicals followed by 20 (11 compounds) and 21 (12 compounds). More antidiabetic compounds were observed in fraction 17. In vitro antidiabetic activity was performed using these three column fractions for inhibition of α-amylase, α-glucosidase, sucrase and glucose. Strong antidiabetic activity was observed in 17 fraction and they inhibited all the above enzymes at rate followed by 21 and 20. The common phytochemical in all the extract is octadecenoic acid. It was used for GEMDOCK to study the interaction with enzymes. octadecenoic acid can be seperated and used as antidiabetic agent.