To elucidate the effect of pressure on liquid fuel boilover, a series of field experiments were carried out using a portable measuring setup at Hefei (Alt.: 0 m, P: 101 kPa) and Lhasa (Alt.: 3650 m, P: 64 kPa). It is found that for a given size of pan, the boilover premonitory onset time tp and the boilover onset time tb are delayed; the intensity of boilover is weaker in low pressure. For a given pressure, tp and tb in larger pan are shorter. In addition, the boiling point of water is still the critical of boilover premonitory period in low pressure, and the critical temperature at the interface is reduced as pressure drops when boilover occurs. Then a prediction equation was made to explain the effect of atmospheric pressure on tp and tb, which proves that the pan diameter has a negative correlation against with tp and tb, and there is a negative correlation between the boilover premonitory onset time tp and the low pressure PL when PL > 10 kPa.