Abstract: Forced convection condensation pressure drops were experimentally determined for a horizontal micro-fin tube (2 m length, 11.44 mm ID) with HC290-oil mixtures. The oil was Suniso 3GS, widely used in refrigerant systems. The oil concentrations ranged from 1.95% to 5.28%. The micro-fin tube is a internally enhanced tube, which has 60 fins with a height of 0.25 mm and 20° spiral angle. The condensation temperatures varied from 40 ℃ to 45 ℃ and the refrigerant mass flux varied from 40 kg•m^-2•s^-1 to 220 kg•m^-2•s^-1. The pressure drop on the test section (inlet vapor quality 1, outlet vapor quality 0.1—0.25) increased greatly as refrigerant mass flux was increased while oil concentration showed negligible effect on pressure drop. Meanwhile based on Kaushik and Azer correlation modification, a correlation suitable to the experimental data was obtained.