This study employed Fourier Transform Infrared (FTIR) spectroscopy to systematically compare the structural characteristics and relative distribution of α-solanine in different parts of potatoes, eggplants, and tomatoes, aiming to explore the applicability of FTIR in rapid screening and qualitative identification of this compound. Spectral peak matching with the α-solanine standard revealed the presence of α-solanine-related structures in various tissue types across all three Solanaceae vegetables. Absorbance ratio analysis showed that the green skin of potatoes, the white skin of eggplants, and tomato seeds exhibited stronger infrared responses within their respective samples, suggesting a degree of tissue-specific accumulation. These findings indicate that α-solanine exhibits species- and tissue-level spatial variation in plants. FTIR thus holds potential as a preliminary tool for screening toxic steroidal alkaloids in plant-derived foods. The results provide foundational spectroscopic evidence to support further exploration of distribution patterns and infrared-based identification methods for glycoalkaloids.