Impingement cooling has been widely used in turbine components, including endwalls, vanes and blades. Numerous investigations focus on single or multiple arrays of jets, which are typically in parallel connection. Very few studies considered jets in series connection, except for some impingement structures used in the trailing edge. Present study selected a series of double wall cooling structures using impinging jets both in series connection and parallel connection. Structures with different connections and geometry parameters were located inside a piece of super alloy to protect the substrate from the high temperature on the external side. Conjugate heat transfer simulation was implemented in this paper with a CFX solver to get the aero-thermal characteristics of the cooling channels. Work condition with power plant operating temperature and pressure was applied. Results indicate that jets linked in series enhance the heat transfer on the target surface both upstream and downstream. The increase of pressure drop induced by series-linked jets is slower than the increase of heat transfer. Conjugate heat transfer analysis implies a potential of coolant saving and pressure saving for series-linked jets.