The invention relates to an aseismatic reflection sheet device, which includes a reflection sheet, a weight support element, an angle fixed adjustment module, a base plate and at least a sliding module. By the composition of above structure, one side of the weight support element is fixed on a vehicle windshield and the weight of the aseismatic reflection sheet device is mostly supported by the part of the weight support element, so that the reflection sheet does not be affected by shocking of the vehicle dashboard, to thereby provide support to the reflection sheet and the vertical and horizontal angle may be easily adjusted.