It is clear that, king Ptolemy "Philadelphus" was affected by the legend of Osiris and what had accured to the four brothers, Osiris "Wsir",Isis "Ast", Seth "stX", and Nephthys "Nbt-Hwt", and specially what had happened to god Osiris and his beloved sister-wife Isis. Therefore, this effect appeared clearly in the behaviour and deeds of king Ptolemy II “Philadelphus"as manifested in there cases. Firstly in honour of both Osiris and Isis he built the temple of Osiris anthe city of Pithom and the great temple of Isis at the Island of Philae. Secondly by his marriage to his beloved sister-wife queen Arsinoe II as the case of Osiris and Isis in the legend. so "Philadelphus" is considered the first Ptolemaic king who married his sister. Thirdly, by honouring and deifying both of his dead father Ptolemy I "Soteros" and his dead mother queen Berenike I and then his deifying his beloved sister-wife queen Arsinoe II. imitating Isis when she honoured her dead husband Osiris and Horus "Hr"when he honoured his dead father Osiris and his beloved mother Isis. Thereon both king Ptolemy II “Philadelphus" and his beloved sister-wife queen “Arsinoe II" become representing god Osiris and goddess Isis on the earth. Therefore, this research sheds light on the theme of " The Effect of the Legend of Osiris on the behaviour of king Ptolemy II "Philadelphus".