The invention relates to a control device for oil operation of an oil field, in particular to an application of a wellhead-testing device for a deviation prevention test to an oil field. The application comprises following steps: sealing a polish rod sealing seat to be eccentric to the center of a wellhead for 5 mm; loosening a pressing cap and rotating a sealing seat for 360 degrees; automatically adjusting to the proper position with an oil-pumping the polish rod; designing a lower-rotating hanger to a rotary eccentric hanger; and performing 360-degree rotation of the rotary eccentric hanger; under effect of a thrust ball bearing to achieve concentricity of the polish rod and an oil tube for 360 degrees when the position of the oil-pumping the polish rod is deviated and the position for offset adjustment of an upper packing seat is not enough in order to ensure that the device, the oil-pumping polish rod, an oil sleeve pipe are kept concentric and do not need calibration in other modes. The application of the well-testing device for the deviation prevention test to the oil field has following beneficial effects: the structure is compact and helps effectively solve problems such as inability of automatically adjusting concentricity between equipment during installation of a wellhead device for oil extraction and annulus and replacement of a sealing mechanism, the necessity of dismantling a rope hanger for a pumping unit during replacement of sealing fillers and the likelihood of damaging a valve cavity when a rubber gate is closed.