The method of lines is used to analyze the influence of dielectric substrates on uniplanar EGB structure. The analysis process is introduced. According to periodic boundary conditions, one unit cell has been isolated as the calculation region, and the method of lines is used to get the propagation equation of potential function in different interfaces of medium layers. By combining the conversion relationship between field component and potential function on the continuity condition of the tangential field components in interfaces, eigen value equations are established, and the frequency band diagrams of eigen mode are obtained to describe the surface wave bandgap of EBG structure. The method is used to do a series of calculations on surface wave bandgap with dielectric substrates of different dielectric constants and different thicknesses. Through analysis of calculation results, six conclusions are obtained on the influence of dielectric substrates, which can provide some references for the design of uniplanar EGB structure.