Technology of building up industrial Ethernet and its' reliability are researched in low-voltage distribution system. The format of industrial Ethernet are divided into process control Ethernet, field control Ethernet and device Ethernet. Structure of building network, characteristic of. network and technology of building network are analyzed at length and point out that network format of combining field bus with industrial Ethernet is comparatively propitious to modem corporation at current engineering level, namely performance price ratio of field control Ethernet is comparatively high.