A flexible tri-band microstrip antenna is proposed to address the issue of narrow wireless signal response ranges in wearable devices within complex application scenarios. This antenna employs a double “T”-shaped+double “L”-shaped surface structure to achieve resonance in the microwave frequency bands of 2.5 GHz, 3.5 GHz, and 5.4 GHz. Polyimide serves as the substrate material, while nano-silver is utilized for the radiating patch, and aconductive material is applied on the ground plane to ensure flexibility. The antenna was analyzed using ANSYS HFSS to constructa model and conduct simulations. Fabrication utilized the microdroplet jet 3D printing process, effectively resolving the high cost and complexity associated with traditional MEMS processing in flexible electronics. Finally, field emission scanning electron microscopy was employed to analyze the printed surface morphology, and a vector network analyzer was utilized to test return loss, bendability, and fatigue resistance of the completed antenna. The test results were consistent with the simulation outcomes, demonstrating excellent bending performance of the antenna.