An overview of the mechanisms for mechanofluorochromic behaviors based on organic/polymer systems has been provided, and the most significant developments in understanding the origin of mechanofluorochromism have been highlighted. The views are mainly focused on the intermolecular effects and intramolecular effects on mechanofluorochromism, including excimer forming, phase structural transition, J- or H-aggregation and intramolecular coplanarity and so on. It should be helpful to researchers to understand more deeply the relationships between the molecular structures and the mechano-responsive behaviors.