This paper reveals the flame pulsation behavior of conduction-controlled rectangular hydrocarbon pool fires in a sub-atmospheric pressure. Experiments are carried out in both normal- (100 kPa; Hefei city, altitude 50 m) and reduced (64 kPa; Lhasa city, altitude 3650 m) pressure atmospheres, using rectangular ethanol pool fires with the same area S (36 cm(2)) but different aspect ratios (long side divided by short side n = L/W = 1, 2, 3, 4, 8). Results show that the flame pulsation frequency of the pool fire changes small with pressure, meanwhile increases with aspect ratio, which can be well characterized by a non-dimensional function between Strouhal number (St) and Froude number (Fr). (C) 2014 Elsevier Ltd. All rights reserved.