Embodiments of the present application provide an intra-band combiner-divider and a multisystem combining platform, and the intra-band combiner-divider includes: a first-level duplexer, an intra-band combination unit, an intra-band division unit, and a second-level duplexer. In the embodiments of the present application, two ends of the intra-band combiner-divider are connected to the first-level duplexer and the second-level duplexer, so that the intra-band combiner-divider can separately process uplink and downlink signals, thereby reducing PIM of a communication system and improving receiver sensitivity of a base station.