The magnetic tunnel junction (MTJ) device employing inverse Heusler alloy as electrode has great potential for application in spintronics. In this work, we performed first-principles calculations combined with nonequilibrium Green's function to study the spin transport properties of Heusler alloy based Ti2CoGe/MgO/Ti2CoGe MTJ with various atomic terminations. The calculated interface free energy (γ) indicates that TiCo-terminated interface could be easily formed than TiGe-terminated interface, and the interface containing pure Ge atom is the most favorable owing to its lowest γ. Spin transport calculations reveal that tunnel magnetoresistance (TMR) ratio in MTJ with natural TiCo terminated interface (1.58 × 104) is higher than that with natural TiGe-terminated interface (2.99 × 103). When the interfacial Ti atom in TiCo-terminated interface is substituted by Co atom, the transport ability of majority spin electrons is promoted. Moreover, our calculation indicates that the MTJ with the interface containing pure Co atom possesses the largest TMR ratio of 9.51 × 105. Our work paves the way for the fabrication of Ti2CoGe based MTJ for practical application in spintronics.