Based on the experiments with the Coupled Forecast System version 2 (CFSv2), the mechanism by which the Madden-Julian Oscillation (MJO) modulates the North Atlantic Oscillation (NAO) is investigated. To isolate the cyclic MJO heating with an eastward propagation over the Indian Ocean and western Pacific, three sets of experiments are conducted with spatio-temporal varying heating added to the model’s internally generated heating. The results suggest that the anomalous MJO heating over the Indian Ocean, rather than the western Pacific, dominates the formation of the NAO anomaly in the following 10-20 days. The MJO heating triggers a westward propagation of the storm track that influences Europe, complementing the eastward pathway of influence via the North Pacific. Both pathways contribute to an enhanced storm track over the North Atlantic and the positive NAO anomaly. The Eurasian pathway is less important for the formation of the negative NAO anomaly.