Based on the principles of gravity-flowing water transfer, near-by water transfer and technological feasibility, 72 inter-basin water transfer projects and related inland waterway networks for grain shipping in nine regions in the world were designed using the spatial analysis function of geographic information system. The grain output increase potential in non-water- receiving areas and water-receiving areas of nine water-transferring irrigation districts were calculated using the Miami Model on light-temperature and climate productivity. The water shortage grade of the water receiving area was evaluated, and the economic benefit and feasibility of the water diversion project were roughly analyzed by tech-economic evaluation. The main conclusions are that the potentials of grain output increase in water-receiving areas and non-water- receiving areas are 3.618 billion tons and 1.172 billion tons respectively, totaling 4.790 billion tons, which is slightly higher than the predicted world's food output increase of 4.056 billion tons by 2100. Most water diversion projects are efficient economically with strong feasibility, and only a few water diversion projects' economic efficiency are poor, but the feasibility can be improved by optimizing the designation. The authors are cautiously optimistic on the global food supply situation in the future, and advocates the adoption of an aggressive global food production strategy to secure the world's food supply.