The invention discloses a spraying path for large area automatic spraying application occasions, such as spraying of building waterproof materials, and a path control method thereof. By means of segmenting (or not) a construction site, a large area construction method of taking a construction alignment line as reference to carry out path planning and control is provided. The method is not limited to large area spraying application, also can be used for other large area path control. Two guide flat plates provided in the invention cooperate with a movable spraying mechanism to execute path control, thus, complexity of path planning can be reduced greatly, meanwhile, the need of first executing complex path planning and processing according to construction drawings is avoided, technical requirement on constructors is reduced, cost is decreased, and operation efficiency is improved.