The molecular structure , configuration and the environmental effect on the fluorescence emission of or2 ganic compounds are tremendous important . The emissive behavior and mechanism are discussed with the decay process of excited state of compounds , especially , with the photo2physics and photochemistry , such as the molecular structure hin2 drance and the bridging structure ; the photo2induced charge transfer , electron transfer and their transformation ; the twist2 ed intra2molecular charge transfer (TICT) ; the interaction between emissive molecule and molecule of solvents and the fa2 vorable configuration existed in the process of molecular emission. The study and grasp of theory and knowledge in this field will be useful for the design and synthesis of compounds with high fluorescence quantum yield , and will be useful for the explanation of different behaviors occurred in experiments , and for the application of these compounds in different condition. In this paper , a large amount of examples of emissive compounds have been listed and discussed in detail