The invention discloses an analysis method for narrowing a transmission capacity gap between an operating stage and a planning stage. The analysis method mainly comprises the steps of building a simulation model by a simulation tool; formulating a unified fault checking standard at the operating stage and the planning stage; determining a reasonable boundary condition conforming to the actual development trend of a power grid at the planning stage; and improving the transmission capability of the power grid at the operating stage. The defects that the research on the aspects of analyzing the transmission capacity gap between the operating stage and the planning stage, proposing a technical scheme for narrowing the transmission capacity gap between the operating stage and the planning stage and the like in the prior art is not deep enough and the transmission capacity of the actual power grid at the operating stage is often lower than the design capability at the planning stage are overcome; the inherent attributes of the power grid are improved; the cognitive ability of power grid characteristics is improved; the power transmitting and receiving capabilities are fully developed; guidance of computational analysis of the transmission capacity at the planning stage is facilitated; and the transmission capacity of the power grid at the actual operating stage is also improved.