To reduce the soil heat loss from both horizontal and vertical direction，this study took no heat insulation panel served as the contrast，and set external and built-in thermal insulation material（EPS）treatments，on the premise of same value of foundation’s thermal resistance，to explore the effects of insulation panel with different position on soil temperature and tomato yield in greenhouse．The results showed that both 2 treatments had significant higher heat preservation effects than that of the contrast．The insulation effect of the built-in heat insulation panel was better than that of the external insulation，and the soil temperature increased 0.5 ℃ and 1.3 ℃ on average in horizontal direction compared with external insulation panel and the contrast group．Ground temperature in vertical direction was significantly better than that of the external（lifting 0.6 ℃ by average），which was significantly higher than that of the contrast（lifting 1.3 ℃ by average）. Within 5-25 cm，the warming amplitudes first increased and then decreased along with the topsoil depth increasing．The tomato root system activity was significantly better than that of the external insulation panel and extreme significantly higher than that of the contrast．The tomato yield was increased by 10.9% and 29.1%，respectively than that of the external insulation panel and the contrast．In summary，the built-in insulation panel could effectively improve the indoor soil temperature in both horizontal and vertical direction，keep the temperature uniformity at different locations，and maintain the root system activity，tomato yield both in improved position．