The invention discloses a high-precision Ethernet timing device which is characterized in that hardware comprises a time processing module CPU (central processing unit), the time processing module CPU is connected with a time processing field programmable gate array (FPGA) through a BUS and is connected with a GPS (global position system) receiving module through a serial port as well as connected with an IEEE1588 (Institute of Electrical and Electronic Engineers 1588) ground synchronization network module through a timing signal; the IEEE1588 ground synchronization network module comprises an IXP425 processor and an IEEE1588 FPGA port, a low-temperature drift crystal oscillator is used as a crystal oscillator source to be accessed into an FPGA phase-locked loop, and a time clock port FPGA, the IEEE1588 ground synchronization network module and the time processing module CPU are provided with timing signal output ports. The invention can be used for building an IEEE1588 ground time synchronization network and supporting clock mutual automatic switching, and can achieve timing precision of 100us in an electric system II region Ethernet under the condition of not supporting IEEE1588 by a router switch and the like.