The invention discloses a special high temperature resistant foliar fertilizer for brassica rapa var. chinensis and a using method thereof. The foliar fertilizer is mainly used for foliage spray on brassica rapa var. chinensis under the condition of high temperature in summer. The foliar fertilizer comprises 25-30% of urea, 20-40% of monopotassium phosphate, 4-6% of borax, 1-2% of ammonium molybdate, 10-15% of zinc sulfate and 10-15% of calcium nitrate by weight. A foliar fertilizer spray method comprises the following steps: spraying the foliar fertilizer for the first time (the mixing ratio of the foliar fertilizer to water is (1 to 30)-(1 to 50)) at the initial stage of the seedling stage of brassica rapa var. chinensis, namely the stage at which two true leaves emerge, and spraying the foliar fertilizer (the mixing ratio of the foliar fertilizer to water is (1 to 15)-(1 to 20)) after five true leaves emerge, wherein the spray frequency does not exceed three times; and the foliar fertilizer is sprayed in the morning or in the evening in sunny days. The foliar fertilizer has the special effect of high temperature resistance, has comprehensive nutrients, is low in cost, is convenient to operate and has the effects of obviously relieving high temperature damage of brassica rapa var. chinensis in summer and obviously increasing the yield of the leafy vegetable brassica rapa var. chinensis in summer.