Tribological properties of key engine components show the big gap between domestic automotive industry and international counterpart. Diamond-like carbon (DLC) coating technique can effectively over come tribological problem of key engine components. Usually, high internal residual stress (up to 10 GPa) generate din deposition process will lead to failure of pure DLC coatings. Application background of DLC coatings in the field of automotive components was analyzed firstly, origin of internal stress in DLC coatings was discussed, and research status of internal stress reduction in DLC coatings by elemental doping was reviewed emphatically. Common doping elements could be classified into carbide forming elements and non-carbide forming elements on the basis of chemical property. However, the elements in this paper were classified according to constituent elements of doping elements instead of other approaches. Advantages and disadvantages of various doping methods and doping elements were analyzed systematically by starting with single- and multi- element doping. On this basis, it was pointed out that objects of studies on internal stress reduction in DLC coatings by elemental doping developed from single element in the beginning into multi-element doping gradually; and from carbide forming elements and non-carbide forming elements into multi-element co-doping of carbide forming elements and non-carbide forming elements. Microstructure of studied DLC coatings developed from amorphous structure into multi-element and multiphase structures, so as to obtain better comprehensive mechanical properties.