An analytical solution based on non-tension Pasternak foundation composite beam with considering soil shear and interlayer disengaging for the double-block ballastless track, is derived to study the influence of uneven settlement of the subgrade on its deformation. Heaviside step function is introduced to describe the disengaging behavior between the track and the subgrade, and the differential governing equation is solved by finite difference method. A three-dimensional beam-body space finite element model is also established to verify the applicability of the analytical model and determine its scope of application. The results show that when the settlement deformation of the subgrade is relatively gentle, the calculation results of the analytical model and the finite element model are almost indistinguishable, the deviation of the two models is getting larger as settlement of the subgrade exacerbated; For a given subgrade settlement wavelength of 20 m, when the settlement amplitude reaches larger than 21 mm, the analytical model is not applicable; Under the given condition that settlement amplitude of the subgrade is 20 mm, the analytical model is applicable to the subgrade settlement condition with a settlement wavelength greater than 19.8 m.