The disclosure discloses an organic photoactive layer composite ink, an organic solar cell and preparation methods thereof. The organic photoactive layer composite ink includes an electron donor material, an electron acceptor material, an organic amine compound and an organic solvent. According to the disclosure, through an interaction between the organic amine compound and a photoactive layer material molecule, the photochemical reaction of the active layer molecule can be effectively inhibited, the photostability of the photoactive layer material is significantly improved, and hence the stability of the solar cell is greatly improved. The organic solar cell prepared by the disclosure has the advantages of high stability, long use service life and the like, and working properties such as energy conversion efficiency are also effectively improved; meanwhile, the organic solar cell is simple and convenient in preparation process, low in material cost and high in economic benefits.