Using smartphones to explore the physical laws of musical instruments is both interesting and scientific．In order to explore the vibration law of guitar strings，it designs an experimental scheme based on smartphones and mobile applications (Phyphox)． By quantitatively measuring the distance，diameter and vibration frequency of guitar strings，the experimental results confirm the vibration law of guitar strings，and the results show that the method is highly feasible and effective．The research is helpful to understand the physical law of guitar string vibration and the principle of guitar sound．The research project reflects the idea of“from

life to physics，from physics to society”．