The invention relates to an organic electroluminescent device and a manufacturing method thereof. The method comprises the following steps: 1, forming a first electrode on a substrate; 2, continuously forming a non-photosensitive organic insulating material and a positive photoresist on the substrate, adopting a mask plate to perform exposure on the positive photoresist, performing developing andetching, and retaining the positive photoresist to form an insulating layer pattern; 3, forming the positive photoresist on the substrate after the step 2, adopting the mask plate capable of forming an isolation pole to perform exposure and developing on the positive photoresist formed in the step 3 so as to form an isolation pole pattern; 4, forming an organic material layer on the substrate after the step 3; and 5, forming a second electrode on the substrate after the step 4. The method avoids adopting a photosensitive organic insulating material with high price, can reduce the production cost of the insulating layer, and solves the problem of unstable contact caused by material variance between the insulating layer and the isolation pole.