Abstract: The A oilfield in the Bohai bay basin is the first pilot test area for thermal recovery of heavy oil in the sea in China. Horizontal wells are developed by multi-element thermal fluid huff and puff. With the increase of huff and puff cycles in thermal recovery wells, gas channeling between wells is prominent, which seriously affects oilfield production. By taking horizontal wells in thermal recovery area as the research object, the main controlling factors of gas channeling are studied from both internal and external aspects. The results show that gas channeling is easy to occur from low part to high part of the structure, and the possibility of gas channeling between wells with the same structural amplitude is small. The horizontal section is prone to occur gas channeling along the direction of abandoned river channel and lateral interlayer. In the subsequent heat injection process, the area with large gas storage is liable to occur gas channeling. The formation pressure drops rapidly, which leads to the relative increase of gas-liquid ratio under the same injection conditions, increasing the sweep radius of gas and increasing the possibility of gas channeling. Based on the field practice, this paper puts forward the control of gas channeling in multi-well area huff and puff, which can effectively suppress the gas channeling in the new round of huff and puff, and improve the development effect of oil field.