In this study, we consider a diffusion system of the Keller-Segel type, which is pivotal in describing the underlying mechanisms of pattern formation. First, the heteroclinic orbit for the degenerate case is investigated by constructing an invariant region. Furthermore, the persistence of travelling waves in Keller-Segel systems in the presence of local or nonlocal delay is respectively established. The geometric singular perturbation theory along with Fredholm theory are the foundational analytical tools utilized in this study. Eventually, the asymptotic behaviors of the travelling waves are elucidated, offering new insights into their dynamic properties.