An assembling surgical access device includes a flexible tube and a connecting structure. The flexible tube includes a tube body and a positioning portion connected to the tube body. The connecting structure is connected to the flexible tube, and includes a housing and a tube fixing member. The housing includes a side wall, an end wall, a fixing portion and a tube hole. The fixing portion is connected to the positioning portion of the flexible tube, and the tube body is disposed through the tube hole. The tube fixing member is engaged into the side wall so as to position the positioning portion between the end wall and the tube fixing member.