The invention relates to a transformer oil-oil bushing auxiliary detection system, which comprises a detection auxiliary device, a detection instrument, a handheld terminal and a background monitoringsystem, wherein the detection auxiliary device comprises an insulation cap and a ground lead-down wire; the detection instrument comprises a control unit, a controllable switch driving unit, a sampling unit, a Bluetooth communication module and a connector; the handheld terminal comprises a data processing unit, an image acquisition module, a clock unit and a storage unit; and the background monitoring system comprises a data transmission unit, an automatic data import unit and an expert assistant decision making system. The transformer oil-oil bushing auxiliary detection system changes the situation that the oil-oil bushing cannot carry out live detection and fills the blank in the field. The latent defects of the oil-oil bushing can be conveniently found out, a basis can be provided fora bushing condition maintenance strategy, and safe and stable operation of an oil-oil bushing transformer is effectively ensured.