This research aims to study phytochemicals and potential of Mapok (Parinari anamense Hance) extracts to inhibit germination and growth of Barnyard grass (Echinochloa crus-galli) a common weed in the rice fields. Organic solvents extracted the part of fruits barks and leaves of Mapok included hexane ethyl acetate and methanol. Crude extracts compose of fruit hexane extract fruit ethyl acetate extract fruit methanol extract bark hexane extract bark ethyl acetate extract bark methanol extract leaves hexane extract leaves ethyl acetate extract and leave methanol extract. Crude extracts were tested of phytochemical tested of germinating inhibition root length inhibition stem length inhibition and dry weight inhibition of Barnyard grass. Leaves ethyl acetate extract showed highest inhibit germination and growth of Barnyard grass The leave ethyl acetate extract was separated by column chromatography to yield nine fractions (F1 – F9 fraction) and tested inhibit germination and growth repeating. The results showed that 1. The crude ethyl acetate extracts from the bark of Mapok at a concentration of 3000 ppm showed the highest inhibited percentage of germinating inhibition root length inhibition stem length inhibition and dry weight inhibition. 2. Fraction F8 of leaves ethyl acetate extract showed the highest inhibited percentage of germinating inhibition root length inhibition stem length inhibition and dry weight inhibition.