The work aims to optimize micro-arc oxidation (MAO) electrolyte formula for Ti2AlNb alloy and improve wear resistance of MAO coatings on Ti2AlNb alloy. Effects of Na2MoO4 concentration on morphology, element composition and phase structure of MAO coatings on Ti2AlNb alloy were investigated in silicate-phosphate electrolyte system by virtue of SEM, EDS and XRD. Friction and wear properties of MAO coatings were tested with ball-disc wear tester. After the addition of Na2MoO4 in the electrolyte, growth rate of MAO coatings increased, Mo element appeared on the MAO coatings and Mo content increased gradually. Friction coefficient and volume wear rate of MAO coatings were reduced as Na2MoO4 was added in the electrolyte. However, the wear resistance of MAO coatings did not increase linearly with the increase of Na2MoO4 content. In the system with 6 g/L Na2MoO4, the friction coefficient of MAO coating reduced to nearly 0.25, and the volume wear rate was only 1.20×10?3 mm3/(N?m), and the surface featured in slight abrasive wear. Na2MoO4 in the electrolytes participates in the film-forming process, plays an important role in promoting growth of MAO coatings on Ti2AlNb alloy and can effectively improve its wear resistance.