The influence of protein on the superior properties of NR was analyzed in term of sacrificial bonds. It was found that the presence of the naturally occurring sacrificial bond provided by protein increases the tensile strengthen and toughness, furthermore prolongs the fatigue life of NR. The superior properties of NR are due to the combine effect of the vulcanized network and the pseudo network constructed by the linked protein and other non-rubber components. The breaking down of the weak pseudo network could provide effective energy dissipation to avoid material failure. The regeneration of the pseudo network helps to preserve the sacrificial bonds, which ultimately leads to the remarkable fatigue resistance of NR. The impact of protein of the network structure is essential to its effect on the properties of NR.