A radio frequency (RF) switch device has at least two RF switch units, each RF switch unit having an output terminal and at least two input terminals. The RF switch units select one channel of RF signals from several channels of the RF signals that are supplied as inputs to their input terminals for emission as an output from their output terminals. A magnetic resonance imaging system and an RF signal transmission method employ such an RF switch device. The use of such an RF switch device reduces the number of channels of the RF signals that need to be further transmitted, which in turn reduces the number of the corresponding long RF cable channels and the number of channels of the subsequent devices, thereby preventing waste and reducing the cost of the system. Moreover, if the subsequent devices include a receiver coil channel selector, then the complexity of the receiver coil channel selector will also be reduced as the number of RF signal channels is decreased.