Post-translational modifications (PTMs) of proteins play a crucial role in living organisms, altering the properties and functions of proteins. There are over 450 known PTMs involved in various life activities. LSD1 (lysine-specific demethylase 1) is the first identified histone demethylase that can remove monomethylation or dimethylation modifications from histone H3 lysine K4 (H3K4) and histone H3 lysine K9 (H3K9). This ability of LSD1 allows it to inhibit or activate transcription. LSD1 has been found to abnormally express at the protein level in various tumors, making it relevant to multiple diseases. As a PTM enzyme, LSD1 itself undergoes various PTMs, including phosphorylation, acetylation, ubiquitination, methylation, SUMOylation, and S-nitrosylation, influencing its activity and function. Dysregulation of these PTMs has been implicated in a wide range of diseases, including cancer, metabolic disorders, neurological disorders, cardiovascular diseases, and bone diseases. Understanding the species of PTMs and functions regulated by various PTMs of LSD1 provides insights into its involvement in diverse physiological and pathological processes. In this review, we discuss the structural characteristics of LSD1 and amino acid residues that affect its enzyme activity. We also summarize the potential PTMs that occur on LSD1 and their involvement in cellular processes. Furthermore, we describe human diseases associated with abnormal expression of LSD1. This comprehensive analysis sheds light on the intricate interplay between PTMs and the functions of LSD1, highlighting their significance in health and diseases.