The lubrication performances of diamond like carbon (DLC) films were investigated by a ball-on-disc tribometer under perfluoropolyether (PFPE) oil lubrications. The influence of nano lubricant additives in PFPE oil on the tribological properties of DLC films was evaluated. The experimental results show that the solid-liquid synergy lubrication is beneficial to improve the tribological properties of the steel-related friction system and the tribological properties of the friction pair are significantly influenced by lubrication modes and the types and contents of nano lubricant additives under PFPE oil lubrication. The friction system exhibits super low friction behaviors under PFPE oil with nano MoS2 lubricant additive lubrication due to the excellent compatibility of nano MoS2 additives with PFPE oil. Coefficient of friction (CoF) of the friction system is as super low as 0.02 under PFPE oil with 0.2wt.% nano MoS2 additive lubrication. Superlow friction mechanism is attributed to the pointlike contact of nano MoS2 additive as soft phase and the excellent diffusion behaviors of nano MoS2 additives in PFPE oil. The potential usefulness of nano MoS2 particles as the lubricant additives in PFPE oil for the steel/DLC films has been demonstrated.