The invention belongs to the technical filed of polymer drugs, and particularly relates to a folate receptor medium, an optical excitation photosensitive drug conjugate and a preparation method of theoptical excitation photosensitive drug conjugate. The preparation method comprises the steps: firstly, folate and amino polyethylene glycol are subjected to an amidation reaction and then subjected to an amidation reaction together with haematoporphyrin HPD, and the polyethylene glycol flexible chain conjugate with folate receptor targeted optical excitation haematoporphyrin genes is obtained. The conjugate prepared through the method can target a tumour cell through the folate receptor medium and enters the cell through endocytosis to accelerate accumulation of the haematoporphyrin in the tumour cell, and through irradiating by purple light or red light with the specific wavelength, accurate diagnosis and treatment can be carried out; and meanwhile, a simple and effective way is providedfor preparing the targeted haematoporphyrin fluorescent molecular drug conjugate.