A method for forming an image sensor package and an image sensor package are provided. The method includes: providing a first substrate and a second substrate which includes a first surface and a second surface opposite to the first surface, and attaching either surface of the first substrate with the first surface of the second substrate with an adhesive layer; forming a groove at the second surface of the second substrate; providing a base which includes a first surface and a second surface opposite to the first surface, where the first surface of the base is provided with a sensing region and multiple contact pads; and attaching the second surface of the second substrate with the first surface of the base, where a cavity is formed between the groove and the base, and the sensing region is located within the cavity.