The extensively used finite element method is a method based on volume discreti-zation, the finite volume method is a method operated on the surface of the con-trol volume, the boundary element method is an one based on boundary surface discretization, and the meshless method is the one constructing the computational algorithm using surrounding scatter points at a collocation point. In this paper, a new numerical method, called Zonal Finite Line Method (ZFLM), is proposed and is applied to solve fluid-solid coupled heat transfer problems. In ZFLM, the computational domain is first discretized into a number of big zones and a series of collocation points are generated in each zone using interpolation formulations. Then, the Finite Line Method (FLM) is used to collo-cate the PDE and related boundary conditions of the considered problem to gen-erate the final system of equations. FLM is very simple in theory and robust in universality, in which only a number of lines are used to solve arbitrarily high-order PDEs with properly imposed boundary conditions. A few challenging nu-merical examples on fluid-solid coupled heat transfer will be given in the paper to verify the correctness and efficiency of the proposed method.