Antiferromagnetic pyrite compound MnTe2 is a newly discovered high-performance thermoelectric material. However, its electric and thermal transport performance remained unexplored so far. In this work, the first-principle calculations based on the density functional theory were applied to predict the electric and thermal transport performance of MnTe2. The band structures showed that Te atoms dominate the band energies near the fermi level. The calculated electric transport performance of MnTe2 from BoltzTraP2 package showed that n-type MnTe2 possesses a higher power factor than that of p-type in the carrier concentration range from 1019 to 1021 cm−3. The peak power factor with electronic relaxation time of n-type MnTe2 at 800 K is 3.05 × 1015 μW K−2 cm−1 s−1 at a lower carrier concentration of 0.78 × 1021 cm−3 while p-type is 2.18 × 1015 μW K−2 cm−1 s−1 at a higher carrier concentration of 1.35 × 1021 cm−3. It suggests that high-performance n-type doped MnTe2 is easier to be obtained experimentally. Due to the low average phonon velocity of 2064 m·s−1, MnTe2 has a low lattice thermal conductivity of 0.72 W m−1 K−1 at 800 K. The calculated charged point defect formation energy of several possible n-type doping elements showed that Y or La substituting Mn atom and Cl or Br substituting Te atom are the most possible n-type doping point defects. Combined with the optimal carrier concentration of 0.78 × 1021 cm−3 at 800 K, stoichiometric A0.07Mn0.93Te2 (A = Y, La) and MnTe1.93B0.07 (B = Cl, Br) are expected to possess high thermoelectric properties reaching the theoretical peak power factor with electronic relaxation time of 3.05 × 1015 μW K−2 cm−1 s−1 and the lattice thermal conductivity of 0.72 W m−1 K−1.