A flexible environmental sensitive electronic device package including a flexible electronic device, a thin film encapsulation (TFE) and a sealing member is provided. The TFE covers the flexible electronic device as well as the sealing member covers the TFE and the flexible electronic device. The sealing member includes a first portion and a second portion, wherein the first portion covers the flexible electronic device and the TFE, and the second portion covers the first portion. Young's modulus of the second portion is between the 0 MPa and 100 MPa. Young's modulus of the first portion is greater than that of the second portion. The thickness of the first portion is less than that of the second portion.