<p>The fuel gas combustion is expanding at high-altitude regions in low-pressure environments with the growing need for energy application and the cross-regional energy allocation. And the flame combustion stability in low-pressure environments would exhibit a significant difference with that in normal pressure. However, the flame oscillation behavior in low-pressure environments is still not fully understood. In this work, the evolution of flame oscillation frequency and flame height at different intermittent levels for rectangular jet flame with different aspect ratios and heat release rate were measured in various low-pressure environments. Results show that the flame oscillation frequency increases with ambient pressure and decreasing aspect ratio of the burner exit, while the heat release rate has no significant effect on the flame oscillation frequency, which could be described by Strouhal number and Froude number with the burner exit perimeter as the characteristic length scale. Furthermore, the flame oscillation amplitude decreases as ambient pressure decreases and is independent of the aspect ratio of burner exit. And the flame height at different intermittent levels shows a linear relationship with the mean flame height, which can be well quantified based on the Boltzmann distribution model considering relative air entrainment strength in various ambient pressures. Finally, a dimensionless model for the maximum flame oscillation amplitude is derived from the flame height at different intermittent levels with the dimensionless model for mean flame height, which shows a great agreement with experimental data. This paper provides the comprehensive experimental data and prediction model for oscillation characteristics for rectangular diffusion jet flames with low pressures, which is helpful to deep understand the combustion stability behavior under high-altitude regions, as well as crucial to accurate hazard assessment and safety distance determination.</p>