The invention discloses a negative-pressure control device for bucket foundation sinking and an application method thereof. The negative-pressure control device comprises a vacuum pump, a negative-pressure storage tank and a control system, wherein an electric contact vacuum meter measures the negative pressure in a bucket foundation, and the device determines whether to turn on a vacuum pump in combination with the set value so that stable negative pressure in the bucket foundation can be guaranteed for a long time; by controlling the on/off of the vacuum pump to stabilize the negative pressure, the volume of the negative-pressure storage tank can be appropriately reduced; and with relatively small negative-pressure storage tank, a relatively large scale of bucket foundation negative-pressure sinking test can be carried out. The device disclosed by the invention has the advantages of simple structure, space saving, long-time supply of stable negative pressure, automatic control of negative pressure and the like.