As an epigenetic enzyme, Lysine-specific demethylase (LSD1) has emerged as a promising target for cancer therapy. Based on the structure of tranylcypromine indazole, a series of LSD1 inhibitors have been designed and synthesized in this work. Most compounds have excellent inhibitory activity against LSD1. The representative compound, 9e, proved to be a highly effective LSD1 inhibitor, with an IC