Abstract: This invention refers to a method for the control of the phenomenon of severe slug in multi-phase flow subsea lines such as those for conveying petroleum from a subsea wellhead to the surface, comprising the installation of at least one secondary line (3), a secondary riser that starts at the downward geometry production line (1) and finishes in the vertical line (2) that conveys the fluids to the production unit, the said secondary line (3) collecting the gas segregated at the top of downward geometry production line (1) at a point B located at a distance "L" from the joint C between the production line (1) and the vertical line (2), and transports the gas to a point A located in the vertical line (2) and a distance "H" from the aforesaid joint C, the pressure differential existing between points A and B ensuring gas flow between said points, with possibilities of installing a control valve (4) in the secondary auxiliary line (3) so as to control the gas flow, the operation of said control valve being monito