Abstract: Composite hetero-structure wall is widely used for the north wall of solar greenhouse in China. A thermal stable thick layer in this type of wall can greatly weaken the heat storage capacity of the greenhouse wall. This study aims to improve the temperature of the thermal stable layer, and thereby promoting the heat storage capacity of north walls in a solar greenhouse. A new type of wall was proposed for the solar greenhouse with a flat Micro Heat Pipe Array (MHPA) wall or heat storage wall. The wall was made by bending the flat micro heat pipe array into a zigzag-shape while mixing the cement mortar to form an MHPA block. Then, the MHPA block and ordinary blocks were built into the MHPA wall. The evaporation section of the flat micro heat pipe array was placed on the inner surface of the MHPA wall, and the condensation section was placed inside the MHPA wall to achieve the purpose of enhancement heat transfer. Two small-scale greenhouse comparison test-benches were set up on site with the MHPA wall (named as MHPA greenhouse) and the ordinary block wall (named as ordinary greenhouse). The evaluation parameters included the temperature of the greenhouse wall, the daily heat storage/release of the wall, and the greenhouse environmental temperature. A systematic investigation was made to compare the characteristics of heat storage/release of the MHPA wall, and the effect of improving the greenhouse thermal environment on representative days. The results showed that the average internal surface temperature of the MHPA wall on typical sunny days (from 17:00 to 9:00 the next day) was 1.6-2.3℃ higher than that of an ordinary wall. From indoor to outdoor, the average temperature inside the MHPA wall for the 0-370 mm area along the wall thickness direction increased by 2.7-4.0℃. During the heat storage period (from 9:00 to 17:00), the average environmental temperature of the MHPA greenhouse was 0.2-0.5℃ lower than that of an ordinary greenhouse, and the average ground surface temperature was 1.8-1.9℃ lower. During the heat release period, the average environmental temperature of the MHPA greenhouse was 1.2-1.5℃ higher than that of an ordinary greenhouse, and the average ground surface temperature was 0.6-1.0℃ higher. The MHPA wall can play the role of “peak cutting and valley filling” in the thermal environment of a greenhouse. The total daily heat storage of the MHPA wall was 8.92%-14.35% higher than that of an ordinary wall, and the total daily heat release was 2.24%-8.07% higher. In the heat storage and release rates of a wall on December 27, the maximum and average heat storage rates of the MHPA wall were 9.63% and 10.99% higher than those of the ordinary wall, and the maximum and average heat release rates were 9.23% and 5.60% higher than those of the ordinary wall, respectively. Moreover, the heat release rate of the MHPA wall was higher than that of an ordinary wall between 23:00 and 7:00 the next day, with an average increase of 11.53%. Therefore, the introduction of the MHPA wall into the wall of a solar greenhouse can effectively improve the heat storage and release capacity of the wall materials for a better thermal environment. These findings can provide a sound reference for the application of a flat micro-heat pipe array to the heat storage wall in a solar greenhouse.