In the electricity market， the effective operation of interruptible load resource not only depends on the interruptible promise， but also lies on active response of interruptible load. The insurance mechanism is introduced into the design of interruptible load contract， which consists of interruptible load insurance and basic interruptible load contract. The utility fixes the premium and compensation and then signs the interruptible load contract with the customer based on the interruptible capability and credit standing declared. This mechanism can induce the customer to improve the credit rating and lower the probability of default， eventually reduce the possibility of payment of compensation and provide interruptible load resource reliably. Finally， a calculation example is given and the results demonstrate the effectiveness of the insurance mechanism.