The double-valve single-flow valve can prevent the fluid from flowing back into the coiled tubing in the wellbore. Large diameter design is adopted to allow steel balls to pass through. Fluid flows in from the upper part of the single-flow valve, pushing the valve disc to flow downward. Because the valve disc is replaced by the valve disc seal and seated with the valve seat under the continuous upward force of the spring, the fluid can not flow upward, thus realizing one-way sealing.