The invention discloses an organic light emitting display panel and a manufacturing method thereof, so as to avoid the problems in the prior art that the manufacturing time is long, large size of a panel cannot be realized and the display panel is prone to fail when an auxiliary cathode is used for reducing resistance. The manufacturing method of the organic light emitting display panel provided by an embodiment of the invention comprises the steps of: sequentially forming a light emitting layer and a cathode layer on a substrate; forming a conductive etching barrier layer on the cathode layer; forming a first encapsulation layer on the etching barrier layer; forming a plurality of via holes exposing the etch barrier layer in the first encapsulation layer by adopting an etching process; and forming an auxiliary cathode layer on the first encapsulation layer, wherein the auxiliary cathode layer is connected with the cathode layer by means of the etching barrier layer at the via holes.