The eddy covariance technique is a micrometeorological method to directly measure the exchanges of carbon, water and energy between the vegetation and atmosphere. The spatial resolution of meteorological observation of fluxes can expand from tens of meters to kilometers. The eddy covariance method is most accurate when the contributing area of the fluxes is topographically flat, and vegetation extends uniformly within the footprint area. Currently there are more than 100 eddy covariance flux observation sites in China. Most of them are established in non-ideal conditions such as forest, undulating surface, patchy canopy area. Therefore, it is important to accurately interpret the ecological representativeness of flux data by evaluation of the spatial representativeness of its footprint in China. This paper reviews basic theories of the footprint, along with progress and applications about footprint functions. It discusses the research focus and difficulties when considering the development of footprint. The footprint of a measurement point is the influence of the properties of the upwind source area weighted by the footprint function. The major effects on the dimensions of the flux footprint are measurement height, surface roughness length, and atmospheric stability. Increase in measurement height, decrease in surface roughness, and change in atmospheric stability from unstable to stable would enlarge the footprint size and move the peak contribution away from the instrument point. The opposite is also true. Footprint functions can be classified into four categories: Analytical model, Lagrangian stochastic model, Large eddy simulation, and Closure model. The footprint result can be applied to experimental design and to evaluate the quality of CO₂ flux data, the variation of CO₂ flux in urban areas, surface energy balance closure and gross primary productivity of landscape scales or regional scales combined with remote sensing. The latest research shows that there is a negative footprint zone in the convective boundary layer and that the location of the footprint peak is closer to the tower for convergent surface flow than for horizontally homogeneous flow. This is reversed for divergent surface flow. Atmospheric advection and non-Gaussian diffusion should be taken into account when building footprint functions. It is necessary for footprint functions within forested areas to consider spatial heterogeneity, clumpiness of vegetation, and instationarity of canopy layer turbulence. Analogical experiments should be implemented in complex terrain, based on the tracer release experiment in ideal conditions.