Photodynamic Therapy(PDT) was a new technology for disease diagnosis and treatment with photosensitizer conducting photodynamic reaction.Photosensitizer was gradually matured through the first-generation photosensitizers-porphyrin and its derivatives,second-generation photosensitizer-phthalocyanine compounds,as well as third-generation photo-sensitizer.The property and synthesis of the three generations of photosensitizers were described.