The paper presents experimental research on the character of air stream flow in an open aerodynamic tunnel with a closed measuring chamber, in which the velocity profile was regulated smoothly through 9 independent axial flow fans. Testing the aerodynamic tunnel was carried out in two stages. In the first stage basic parameters of the air stream were determined for 8 base frequencies of fans operation including dynamic pressure, velocity and quality indices of the tunnel: distribution of velocity uniformity and indices of turbulences intensity, which were referred to averages arithmetic velocities. In the second stage, the effect of regulation of particular fans operation on the distribution of velocities fields in a given measuring sphere of the aerodynamic tunnel, where a mini-wind power plant will be placed, were investigated. Both for a regulated as well as a non-regulated system within higher velocities of the stream approx. 15.80m•s-1 the value of the turbulences intensity index was approx. 1.5%. Control of fans allowed limitation of the range of turbulences intensity indices for the whole range of velocities from 2.8–1.5% to 2.0–1.2%. The presented analysis of results proved that the suggested solution of control of particular fans allows obtaining sufficiently homogeneous air stream, such that real objects of mini –wind power turbines could be tested there.