Due to wiring issues, strain monitoring of mega structures over a hundred meters tall is a challenging task. To achieve strain measurement at key positions of these structures, we propose a sensing method based on near-field passive wireless strain sensors and unmanned aerial vehicle platforms. UAVs can carry signal transmitters of these sensors, approach giant structures, and receive signals from sensors. The sensor consists of a bulk acoustic wave device as a strain sensing unit and a magnetic resonance coupler for wireless power transmission. The experiment shows that the sensor has a resolution of 4 MPa for steel structures and a sensing distance of up to 7 cm. In addition, the fluctuation of sensing distance has little effect on the resonant frequency of the sensor it suggests that the hovering jitter of UAVs will not affect the accuracy of the sensor. In the demonstration section, we demonstrated that sensors can detect strain changes in large amusement facilities such as Ferris wheels, pendulums, and roller coasters. In the future, we will integrate sensing systems into drones to achieve strain measurement of mega structures.