A method for starting a combustion engine (2) in a propulsion system (1) of a hybrid vehicle, the propulsion system includes a planetary gear having three components: a sun gear (10), a ring gear (11) and a planet wheel carrier (12). The output shaft (2a) of the combustion engine connected to a first component of the planetary gear, an input shaft (3a) of a gearbox (3) connected to a second component of the planetary gear and a rotor (9b) of an electric machine (9) connected to a third component of the gearbox. The vehicle is set in an initial position with a suitable gear engaged in the gearbox and with a brake acting on the input shaft of the gearbox. After the electric machine is controlled so that the ring gear is brought into a negative rotation speed (n3) and the output shaft (2a) of the combustion engine is, via the sun gear, brought to rotate with a positive rotation speed (n1) so that the combustion engine may be started.