An insulation detection method includes closing a main positive relay and a main negative relay in a high voltage safety box of each electric cabinet in an energy storage system; controlling an insulation detection board to perform insulation detection at a main power management system, and to report an insulation detection result to a power conversion system; controlling, if the insulation detection result at the main power management system indicates no fault and no instruction of starting insulation detection at the power conversion system is received, the insulation detection board to continue performing the insulation detection; and instructing, if the insulation detection result at the main power management system indicates an insulation fault, a battery management system of each electric cabinet to control the main positive relay and the main negative relay in the high voltage safety box to turn off.