Abstract: A low speed 2-D wind tunnel with flexible wall, self-streamlining test section, has been built at NPU. The present paper expounds the working principle and testing method of the tunnel, the main design characteristics of the flexible-walled test section, pitot-tube measurement of the flow field in the empty tunnel, the considerations of test models and instrumentations. The running program and the calculation method for iterative testings of the 2-D adaptive wind tunnel.The results of the preliminary tests show that, if the relaxation factor is taken between 0.25⁰.60, the test for a cylinder model （e = 13.7%） will converge to the interference-free datum by 2 ⁴ iterations. A procedure for varying the relaxation factor to accelerate the convergence was also studied in the test. For NACA 0012 airfoil model （H/C = 1.28, at a=0）, the results show that, if the relaxation factor is pro-porly chosen, the interference free datum can be achieve by 2 itera tions.