Abstract: For the analysis of plate-shell coupled structures, the coupling edges should be divided by lots of points to calculate if the substructure point receptance method is applied, which is inconvenient. To solve this problem, an improved substructure line receptance method is presented here. Firstly, a coupled model of a cylindrical shell with a floor partition is obtained, based on the substructure theory. Secondly, a modal expansion method is utilized to get the line receptance of the cylindrical shell and the floor partition separately. As a result, vibrating velocities of the plate and the shell can be acquired, to calculate the power flows of the system. Eventually, comparison is carried out among the results calculated by substructure line receptance methods, ANSYS and AutoSEA, respectively. It shows that the method presented here is effective to analyze the vibration power flow characteristics of plate-shell coupled structures over a wide frequency range and the calculation process is simpler compared with that of the substructure point mobility method. Thus, this method is especially suitable for complex structures coupled with lines.