The invention relates to a twisted pair line local control network data conversion device used in the field of industrial distributed control system. In the invention, a standard plug interface is used for an ingoing interface of a main circuit of the device; a cable is used for being communicated with the interface of a data acquisition and processing fastener arranged in a PC in a telecommunication way; an outgoing interface uses a socket interface; a standard 232 extension line is electrically communicated with a TP-485 interface of a MICRO TDC3000 system; an electrical power source uses aDC/DC modular converter to be respectively communicated with a plurality of power input interfaces of electrical elements; input ends of four GUS communication units connected in parallel are respectively connected with corresponding feet of the ingoing interface, the output end is respectively and electrically communicated with the control end of a logic control unit and a TP-LCN communication unit; the output end of the TP-LCN communication unit is correspondingly and electrically communicated with the outgoing interface; the control logic unit is respectively and electrically communicated with the GUS communication units and the TP-LCN communication unit. The device has the advantages of simple structure, reliable principle, convenient abutting joint and low cost.