Recent research on atrium energy efficiency design focuses mainly on the relationship between the architectural geometries and dimensions and the building energy consumption. Achieving referential significance has imposed restrictions on the flexibility of the spatial design of public buildings with atriums. Therefore, introducing dimensionless index parameters for atrium energy efficiency design resolves the contradiction between flexibility and universality regardless of the geometries and dimensions of the atrium. This research proposes three dimensionless energy efficiency index parameters for office buildings with atriums in severe cold region of China. These parameters are span-height ratio (SHR), atrium-building area ratio (ABAR), and orientation-weighted exposed length of side ratio (OWELSR). Annual heating energy consumption simulations are conducted according to the meteorological parameters of the city of Harbin. This analysis normalizes the quantitative outcomes of different types and dimensions of atriums by establishing quantitative relationship models of the dimensionless index parameters and the annual heating energy utilization intensity (EUI) of the building. The optimal value ranges of the dimensionless index parameters are defined to provide better guidance when designing energy efficiency office buildings with atriums in severe cold region of China.