The invention belongs to the technical field of agriculture and discloses a modularized fertilizer applicator suitable for working in mountains and hills. The modularized fertilizer applicator comprises a drilling-fertilizing device, an autonomous guiding device, a hinging-swinging device, electronic equipment, control equipment and a main body framework. By utilizing the hinging-swinging device, the fertilizer applicator can swing in the horizontal direction, is convenient to turn and is simultaneously detached; and by utilizing the autonomous guiding device, the fertilizer applicator can move straightly during normal walking through guide wheels and a rotating damper and can finish directional movement along furrows in drilling and fertilizing processes. By taking circularly utilized iron-lithium batteries as a driving energy source, the fertilizer applicator is environmentally friendly, the energy source acquiring way is simple, and no carbon dioxide is emitted. The fertilizer applicator has the characteristics that the structure is simple, the cost is relatively low, dug holes are deep and uniform, the quantitative and precise hole application of fertilizers is realized, and the operation is simple; and the fertilizer applicator can be autonomously guided and located, is relatively high in efficiency and is suitable for working in the mountains and the hills.