Embodiments of the present invention provide a method and an apparatus for sending a reference signal, and a method and an apparatus for obtaining a reference signal. The method for sending a reference signal includes: determining, based on a resource that is allocated to a reference signal in a basic pattern corresponding to the reference signal and a resource that is allocated to at least one basic pattern in a physical layer transmission unit, a resource occupied by the reference signal in the physical layer transmission unit; and sending the reference signal through the determined resource. It can be learned that, according to the technical solutions provided in the embodiments of the present invention, arrangement of the reference signal in the physical layer transmission unit can be flexibly set.