The invention discloses an air port adjustable static pressure box with uniform outlet air, which comprises a static pressure box shell, an air inlet, an air outlet and a silencing material adhered to the inner surface of the static pressure box shell, wherein a hole plate is arranged in the middle of the static pressure box shell and located above the air inlet, a partition plate is arranged below the hole plate, the space in the static pressure box shell is divided into a steady flow region, and an inlet air region and an outlet air region by the hole plate and the partition plate; and a groove is arranged at the bottom of the outlet air region of the static pressure box shell, a vertical flow guiding section is formed by extending a certain distance downwards along the groove, a slot is arranged at one side of the groove, and a regulating plate with a flow guiding arc section is installed on the slot and moves in the vertical flow guiding section through the depth extending into the slot to regulate outlet air amount of the air outlet. Through introducing the partition plate and the hole plate, the flowing distance of air is lengthened, the ratio of dynamical pressure converted to static pressure is increased, the uniformity of the outlet air is enhanced, the operation noise of equipment is reduced, the requirements for outlet air of the seam air inlet are better satisfied, and the application range of a static pressure box is widened.