The invention relates to a rubber oil and a preparation method thereof. The rubber oil comprises, by mass, 5-10% of No.5 white oil from China National Offshore Oil Corporation, 35-45% of No.15 cosmetic grade white oil and 45-55% of 60N base oil from China National Offshore Oil Corporation. The above three base oils are mixed, and are stirred for 20-30 min to obtain the rubber oil. The rubber oil has the advantages of high initial boiling point, narrow distillation range and high flash point, has greatly better performances than commercial 60 N base oils, and allows satisfactory TPE rubber to be produced without any additive.