The interfacial phase of Ti/ TiCp composite was measured to be Ti2C by TEM and EELS. The cell of Ti2C and the position corrdinates of Ti and C atoms were determined with the knowledge of electron diffraction and crystallography, the regulations of carbon vacancy order distribution were also discussed. There are 48 atoms in Ti2C cell: 32 Ti atoms and 16 C atoms. The Ti atoms occupy the 32 e sites (x is 3/8 or 7/8)and the C atoms occupy the 16 c or 16 d sites in Ti2C space group Fd3m. The C vacancy arrangement is in order in the F111G C layers. The F 111G C layers with 3 / 4 and 1 / 4 occupancies were arranged alternately. There are 6 Ti layers arid 6 C layers during one period in the direction of <111>, the sequence is: