The invention discloses a method for achieving short-cut denitrification by a continuous flow sewage treatment system, and belongs to the field of biological sewage treatment. The short-cut denitrification is an economical and efficient biological sewage nitrogen removal method, and is achieved in an intermittent denitrification treatment system at present, but is difficultly achieved by most of continuous flow treatment systems for nitrogen and phosphorus removal in practical application due to the complexity of operation and control. By adopting the continuous flow nitrogen and phosphorus removal system for processing domestic sewage, the short-cut denitrification is achieved by controlling the sludge return ratio, the nitrated liquid reflux ratio and the hydraulic retention time of an aerobic zone under the operation condition that the dissolved oxygen concentration at normal temperature is 1-2mg/L, the accumulation rate of nitrite is stably maintained at 90%, the ammonium-nitrogen removal rate can be up to over 95%, and the total phosphorus removal rate can be up to over 90%. By adopting the method, the problem that the short-cut denitrification is applied to the biological sewage nitrogen and phosphorus removal system for the continuous flow in the past is solved, the application range of the short-cut denitrification is expanded, and the method can be used for guiding the biological sewage nitrogen and phosphorus removal system for the continuous flow to achieve operation and control of the short-cut denitrification.