With the increasing of building energy consumption and the growing of energy crisis, building energy conservation has become particularly urgent. Exterior wall is the most important part of the enclosure structure in energy saving. Foam concrete is widely used in construction engineering practice because of its good thermal insulation properties. But its use in building facades is still in the exploratory stage. This paper introduces the structure and performance of new foam concrete external wall. Experiments on heat preservation and heat insulation of outside wall insulation, solid brick walls and insulation properties are analyzed. Through the analysis, it is found that thermal insulation performance of foam concrete external wall is far better than the other two walls. In the condition of open air conditioning, the inner surface of the heat value is only 30.4% of external wall insulation with significant energy savings. And foam concrete external wall is more lightweight, its mass is only 57.1% of external wall insulation.