To solve the difficulty of decision making on equipment maintenance and insurance under restricted conditions, based on the principal of randomized service system, setting up the equipment demand forecasting and decision-making modeling. By combining the demand forecasting on equipment maintenance and insurance with the decision making process, conducting a systematic analysis on the basic components, distribution law, denotative method, primary model and evaluating index of the randomized service system, the method of equipment maintenance and insurance forecasting and decision making based on the maintenance efficiency is set forth, the concept of loss function of equipment maintain insurance is established by the examples of equipment maintaining insurance, the feasibility and validity is validated by using examples. The conclusion shows great realistic significance on innovating methods of equipment demand forecasting and decision-making and advancing the building of the precision of equipment maintaining insurance.