The utility model relates to a hydraulic control loop suitable for a field double-box fertilizer applicator. The device mainly comprises an overflow valve (1), wherein the first one-way speed regulating valve (2), the first fertilization hydraulic motor (3), the second fertilization hydraulic motor (4), the second one-way speed regulating valve (5), the one-way valve (6), the three-position four-way electromagnetic reversing valve (7), the gear pump (8), the oil filter (9) and the oil tank (10) can be common manual speed regulating valves or electro-hydraulic proportional flow valves; by meansof the hydraulic loop, on-demand adjustment of the fertilizing amount and variable adjustment of the fertilizing types of two kinds of fertilizer applicators in the field are achieved.