In order to probe the influence of different irrigation methods on the distribution of soil temperature, the paper studied the soil temperature distribution characteristics in the tomato root zone under non-pressure sub-irrigation (NPSI),furrow irrigation (FI) and drip irrigation (DI) in a greenhouse through two years experiment. The experiment comprised of 3NPSI treatments and FI and DI as standard controls. The results show that soil temperatures at various depths were higher under NPSI treatments than either FI or DI; the daily average temperature was 1.02-1.05℃ at 0-25cm soil layer higher under NPSI than under FI and 0.72-0.85℃ higher than with DI. The maximum difference of temperature occurs at 15cm depth. The average diurnal amplitude of soil temperature in the root zone at the same soil depths is 5.4%~10.0% greater under NPSI than FI and DI, and the relation between diurnal amplitude and soil depth could be described by an exponential function. The result can provide basis for the application of non-pressure sub-irrigation in winter growth of tomato in greenhouse .