The invention discloses a field detection device and detection method for insulation performance of low-voltage-side bus packaging material and solves problems in convenient and quick field detectionon insulation performance of the low-voltage-side bus packaging material. The device includes a low-voltage-side bus copper bar connected to an insulation support arranged in an airtight box (12) in asuspension manner, an insulation material layer (7) packaging a bottom edge and two upper bending parts of the semi-square shaped low-voltage-side bus copper bar (6). The packaging height H of the insulation material layer (7) on the semi-square shaped low-voltage-side bus copper bar (6) is 30 cm. A grounding copper bar (3) is arranged between the airtight box (12) and the ground. The top end ofthe semi-square shaped low-voltage-side bus copper bar (6) is connected with an adjustable voltage transformer (8) outside the airtight box (12) through a test high voltage lead (9). A 220V power source (11) and a test voltage regulation controller (10) are connected to the adjustable voltage transformer (8) separately. Working quality of field operation is improved.