Abnormal wear has always been a common concern in engineering lubrication, which sometimes depends on the lubrication. The present work aimed to elucidate the formation mechanism of abnormal non-circular wear scar of GCr15 ball-ball contact in the presence of dibutyl phosphite (DBPI). A detailed characterization of morphology, composition, and structure was performed. The results show that the abnormal wear depended on the chemical reactivity of DBPI, structure and size of wear products. Importantly, wear products exhibited a flocculent structure at the macroscale and had a capsule structure with metal debris encapsulated into an amorphous shell at the microscale. The redeposition of wear products formed a multilayered tribofilm, containing a metal-debrisdominated layer and multiple organic-dominated amorphous layers. The total thickness of tribofilm can be up to 268 nm. Fe3(POx)2, FePOx, Fe[DBPI]2, and Fe[DBPI]3 were the principal composition of tribofilm. The present work elucidates the molecule-dependent abnormal wear of ball-ball contact, which will have wide potential for the additives design and the corresponding lubrication mechanism research.