Under high-speed and heavy-load conditions, rubber sealing products suffer severe wear, leading to reduced service life of key components of equipment. Hard and wear-resistant Diamond-like carbon (DLC) coatings offer a promising solution. While, different from DLC coated rigid substrate, the elasticity and stress distribution combining interfacial deformation of DLC-coated soft substrate show notable discrepancy during tribological test, the related wear mechanism remains poorly understood. In this study, DLC with different Si and O contents (Si/O-DLC) were deposited on nitrite butadiene rubber (NBR). With Si/O content increasing from 3.05 to 8.47 at.% and 2.42 to 7.56 at.%, respectively, the stress in DLC, the hardness and elastic modulus of DLC coated rubber tended to decrease, which enhanced adhesion strength and benefited less cracks for delamination under in-situ tensile testing. Finite element method confirmed that the synergistic improved flexibility together with the reduced mismatch of mechanical properties between Si/O-DLC and NBR, subsequently avoiding stress accumulation and suppressing cracking and spallation. All these contributions enabled the low and stable friction coefficient (COF) for the Si/O-DLC coated on the rubber, specifically with COF less than 0.38 under 5 N and 10 N. The results provide an effective strategy to improve the wear resistance of hard DLC coated flexible rubber in practical working conditions.