Abstract: The present paper gives the results of the slotted wall interference study in two-dimentional transonic wind tunnel.First, a model was tested in the slotted wall test section with two pressure rails. A NACA0012 airfoil was used for the model, Mach numbers were 0.6, 0.75 and 0.9, the angles cf attack were 0°to 3°, the ventilation ratios of slotted wall were 2% and 5%.Second, a simple computing method to assessing wall interference was developed using the transonic small disturbance pressure equationComparing experimental and computed results, we carefully analyze the influence on the wall interference exerted by the variation of ventilation ratio, Mach number and angle of attack. The result shows that the adoption of uneven ventilated wall is benifitial to decrease or even remove the wall interference.