In order to realize the functional integration， information sharing， standardization of interfaces and intelligent of transformer intelligent components（TIC）， overall design and assembling schemes of TIC are proposed based on digital sampling in smart substation. In order to meet the needs of intelligent control， fault diagnosis of TIC， a kind of main intelligent electronic device（IED） for transformer is designed， which is composed of observe and control IED as well as monitoring IED. Observe and control IED can collect transformer three sides dynamic state， steady state， and transient state information， which can be shared by monitoring IED through reliable internal Ethernet. The hardware design scheme of transformer intelligent terminal is introduced， and the digital measurement， intelligent control and non-electric quantity protection functions are realized.