A method is described for operating a parallel hybrid device train (1) of a vehicle having an internal combustion engine (2), an electric engine (3) and an output (5) wherein the electric engine (3) is disposed in the power train between the output (5) and the internal combustion engine (2) and both between the internal combustion engine (2) and the electric engine (3) and between the electric engine (3) and the output (5) is respectively provided a frictionally engaged shifting element (7, 8). In addition, a nominal output torque abutting on the output (5) can be adjusted according to the transmitting capacity of the first shifting element (8) located between the electric engine (3) and the output (5). According to the invention, the transmitting capacity of the first shifting element (8) is adjusted under control according to the nominal input torque required so that the first shifting element (8) has a transmitting capacity needed for producing the nominal output torque on the output (5). Furthermore, an input rotational speed of the electric engine (3) is adjusted under regulation during a starting process of the internal combustion engine (2) in order to keep the first shifting element in slip operation at least during the starting process of the internal combustion engine (2) and to produce the nominal output torque on the output (5).