Based on the fundamental thermodynamic principles, the ordering behavior of the ThMn12-type intermetallics NdFe10-xCoxMo2 were studied using a general four-sublattice model supported with first-principles calculations. The results show that the 2a sublattices are occupied by the rare earth elements Nd exclusively, while the 50% of 8i sublattices are occupied by Mo atoms, 8f, 8j and the rest 50% of 8i sublattices are shared by Fe and Co atoms, which agreed well with the reported experimental results. Site occupancy fractions of Fe and Co atoms vary with temperature in the quaternary alloys due to the partial solid solution of Fe and Co atoms in sublattice 8f and 8j, while they keep constant in ternary alloys upon varying temperature. Co and Fe atoms can substitute each other without affecting the ordering behavior of the intermetallics. In the alloy NdFe5Co5Mo2, with an equal the content of Fe and Co, Fe atoms favor the occupancy of sublattice 8f, while Co atoms prefer the occupancy of sublattice 8j.