The invention discloses a contact network state on-line monitoring/detection device based on public network transmission, comprising a plurality of lower computers and remote upper computers which are installed on a return circuit; the upper computers communicate with the lower computers through a GPRS/GSM wireless network; and a mobile phone can control part of the functions of the lower computers. The remote computer comprises a node operation panel, a power supply monitoring panel, a sampling parameter configuration panel, a time display/recording panel, and a data display/extraction and analysis/ computer panel; the lower computer comprises a main control chip, a trigger circuit, a switch circuit, a sampling module, a power supply monitoring module, a data transmission module, a data transmission auxiliary module, a data transmission switch module, a time service module, a start-up module, an audio sensor module, a state monitoring sensor module, and a self-power supply module. The lower computer utilizes various sensors to collect the state parameters of the contact network structure, current, environment and the internal of the device, and the upper computer displays the obtained state parameters in the panels and records to finally generate a technology report. The invention can collect various state parameters, and realizes full-day, unmanned and independent work.