The objective of the invention is to provide a device for searching a structural element three-component coefficient under the wind effect and a method thereof, and particularly provides a mobile quasi wind tunnel device for testing and researching three components of the structural element through a wind field generated by vehicle movement. The device comprises a transport vehicle and an equipment cabinet which is loaded on a vehicle trunk. The equipment cabinet is provided with a test platform. The test platform is provided with a circular rotating disc used for adjusting a wind attack angle. The circular rotating disc is provided with a support which is used for fixing a force measuring balance and a structural element module. The device is simple and convenient to operate and low in test cost and can use the real environmental conditions so that the device and the method can be a beneficial supplementary method apart from the wind tunnel test and can be widely applied to determination of the three-component coefficient of various structures.