Comprehensive Summary Compared with traditional fluorescent materials with aggregation-caused quenching (ACQ) effect, small organic molecules with aggregation-induced emission (AIE) characteristics show advantages in the field of biomedical detection due to their special structure and optical properties. However, the single function of fluorescent materials can no longer meet the needs of multiple applications. Preparation of multifunctional materials will become a new research craze. In this paper, a D-π-A organic small molecule ( E)-9-Butyl-3-(2-(pyridin-4-yl)vinyl)-9 H-carbazole ( PC) was designed and synthesized by Wittig reaction with modified carbazole group as electron donor (D) and pyridine as electron acceptor (A). The results of X-ray single crystal diffraction, spectral measurement and theoretical calculation show that PC exhibits good aggregation-induced emission properties due to the stacking model of J-aggregation. In addition, we found that PC displays acid-stimulated fluorescence response properties, expanding the application fields of PC in encrypted information transmission, fluorescent ink, and cell imaging, injecting new vitality into multifunctional materials.