The invention discloses a method for applying a fertilizer on oranges. With the method, a leaf fertilizer-application mode is adopted when the orange is in different growth periods (successively a tree vigour restoration period, a period from white flower bud to a bud period, the period of blossom fall to young fruit formation, a young fruit development period, a young fruit expansion period, a summer shoot period, an autumn growth germination period, an autumn growth aging period, a fruit expansion later period, a fruit color changing period and a fruit maturing period), or a mode of combining leaf spraying with flushing for spraying roots is adopted to apply one or a combination of a Bili water-soluble fertilizer, a Zhuangli water-soluble fertilizer, a Huali water-soluble fertilizer, a boron-force water-soluble fertilizer, a fruit setting water-soluble fertilizer, a high-potassium flushed fertilizer, a root force calcium water-soluble fertilizer, a Gaili water-soluble fertilizer, a fruit-expansion flushed fertilizer, a liquid for accelerating rooting and increasing sweetness and a Hongguoli water-soluble fertilizer; thus various nutrient components (especially calcium, magnesium, ferrum, zinc, manganese, boron, copper, molybdenum and the like) required for each growth period are supplemented for oranges, so that the oranges can quickly and sufficiently obtain required nutrient components in each growth period to keep balanced nutrients, thereby ensuring that the tips, the flowers, the fruits and the like of the oranges can normally grow.