In this paper, the Sasa-Satsuma equation, which is applied to the dynamics of the deep water waves, and the pulse propagation in the optical fibers and generally in the dispersive nonlinear media, is investigated. Starting from the first-order Darboux transformation, we construct an N -fold generalized Darboux transformation (GDT) for the Sasa-Satsuma equation, where N is a positive integer. Through the obtained N -fold GDT, we derive three kinds of the semirational solutions, which describe the second-order degenerate solitons, the third-order degenerate solitons, and the interaction between the second-order degenerate solitons and one soliton, respectively. We graphically illustrate the above three kinds of semirational solutions and investigate them through the asymptotic analysis, from which we find that the characteristic lines of the semirational solutions are composed of the straight lines and curves. Expressions of the characteristic lines, positions, amplitudes, slopes, positions and phase shifts of the asymptotic solitons are presented through the asymptotic analysis.