In order to understand the main factors influencing the flow of moistube and determine the relationship between flow and pressure, in the case of different soil initial mass moisture contents（13.83%, 15.49%, 16.27% and 17.72%）and soil bulk densities（1.18g/cm3, 1.21g/cm3, 1.24g/cm3.and 1.26g/cm3）, the completely random experiment design in field of arable land was used to test the influence of different pressures (0m, 0.1m, 0.3m, 0.7m, 1.1m and 2.1m) on moistube flow. The results showed that the moistube had a weak and short duration of selfregulation function of flow with the change of soil moisture content, which was about 44h. The moistube flow was increased quickly and then decreased to steady state, the soil moisture content was increased and then tended to stable state at the beginning of irrigation, it would be in steady state when after 48h of irrigation. Moistube flow was significantly influenced by pressure, soil bulk density and soil initial mass moisture content. Moistube flow was mainly controlled by pressure, there was a significantly liner relationship between pressure and flow within a certain range (the water head was varied from 0m to 2.1m), the determination coefficient R2＞0.85, when soil initial mass moisture content and bulk density was increased, moistube flow kept a downtrend, meanwhile the moistube flow change on the sensitivity of the working pressure was gradually decreased. Moistube flow coefficient k and flow b with zero pressure were not simply determined by the moistube’s characteristics in the model of liner relationship between pressure and flow. The soil initial mass moisture content and bulk density with moistube flow coefficient k showed a significant negative correlation respectively (P<0.05), bulk density with flow b with zero pressure had a significant negative correlation (P<0.05), Moistube flow coefficient k and flow bwith zero pressure can be determined by soil initial mass moisture content and bulk density, thus the moistube flow can be predicted. According to correlation analysis and variance analysis, pressure was the most important factor affecting the moistube flow, then the soil bulk density and soil initial mass moisture content was the least.