It is very important to quantitatively analyze steam chamber expanding and bottom water invading during steam flooding. Firstly, a novel method was established to identify the moment of water invading based on the energy conservation law. Then, a series of experiments were carried out to research the effect of steam flooding through 3D physical simulation and oil-component analysis. The results showed that water invading was recognized through the inflection point of tangent slope of temperature vs. time. Steam mainly migrated in upper layer and hot water moved downwards into bottom layer. The four stages of steam flooding were corresponding to the growth processes of steam chamber, such as expanding, advancing, channeling and overriding. The ultimate oil recovery factor was only 36.00%. The shape of water coning deformed from a triangle to a trapezoid. Finally, the dimensionless volume of water coning was about 32.29%. During steam flooding, the content of oil components gradually changed due to the effect of distillation. The content of light hydrocarbon was higher at the front of steam chamber. However, heavy components mainly occupied the swept zone of steam flooding. The results are important in exploitation practice aiming at heavy oil reservoirs with bottom water.