The invention relates to a multi-frequency transmission device of an collection terminal. The multi-frequency transmission device comprises a transmission host, a disc-type directional antenna, a magnetic ring base, a rotary antenna interface, a multi-frequency antenna, a POE power receiving port and an antenna omnidirectional rotary base, the transmission host and the disc-type directional antenna are connected through the antenna omnidirectional rotating base and realize directional rotation of the antenna. The transmission host and the magnetic ring base are in magnetic connection and are further fixed on the metal interface through the magnetic ring; the transmission host is provided with a plurality of rotary antenna interfaces, and the rotary antenna interfaces are detachably connected with the multi-frequency antenna; and the POE power receiving port is arranged on the transmission host and used for providing electric energy and data interfaces for the transmission host. Omnidirectional and directional enhanced data transmission can be carried out in a wireless signal bad area in multiple frequency modes, the limitation of a signal shielding area is broken through, the structure is simple, the design is reasonable, and the transmission requirement of a power supply company for collection, operation and maintenance equipment is met.