Ice storage system can be used to shift electrical load from on-peak hours to off-peak hours, which can bring mutual benefits to power supplier and consumers. But if it does not operate properly the economic benefit will not be achieved. There is an ice storage system with flake ice maker that have been installed in Donghua University. In this paper, the characteristics of phase-change heat transfer of flake ice maker is studied. According to the different temperature of water washing the plate of evaporator and air conditioning load characteristic, the operation parameters are optimized. The optimized operation strategy of this ice storage system is presented according to its heat transfer characteristic. (C) 2008 Elsevier B.V. All rights reserved.