The traditional SAGD technology in the development of thin oil sands reservoir will affect the production efficiency due to the high viscosity of heavy oil and high heat loss. Consequently, technological advancements are urgently needed to enhance recovery factors in these reservoirs. The paper explores the application of VH-SAGD technology through 2D visualization and 3D simulation experiments. The effects of different well spacing (the horizontal distance between the vertical steam injection wells and the horizontal production wells) on the development of the steam chamber were studied. Then, based on the optimal well spacing optimization results, a 3D simulation experiment is carried out to obtain the real development characteristics of the steam chamber in the reservoir through the temperature sensor in real time. Finally, the production dynamics of each steam chamber in the development stage are analyzed. The experimental results show that reasonably well spacing can promote the development of a steam chamber. The 3D experiment demonstrates that the development of the steam chamber progresses through four stages: forming, longitudinal expansion, lateral expansion, and stabilization. The appearance of a cold oil zone in the shape of a conical bottle between injection and production Wells indicates that the steam chamber is mature and no longer expanding, while the formation of a stable and smooth steam front funnel between injection and production Wells indicates that the steam chamber has entered a stable stage. The experimental results can provide some reference for the development of similar thin layer oil sand reservoirs.