With power system deregulation undergoing worldwide, it's urgent for China to establish multi-level power market in large interconnected power system to better configure energy resources and gain greater economic benefit of power exchanges. But it's not clear how to maintain network security in such environment. This paper therefore suggests a coordination information based security coordination scheme under which the upper-level and lower-level power market can cooperate smoothly for the system security and potential power exchanges among lower-level markets can be greatly boosted. The method of obtaining the coordination information for lower-level market and the transaction scheduling model for upper-level market are also discussed. The suggested scheme is tested on IEEE 30 bus system and proved to be feasible. Numeric results show that the scheme and related algorithms proposed in this paper can make great economic benefit which is near to the ideal results.