In optical test for manufacturing large aspherical mirrors, horizontal test arrangements are used traditionally.Because of the environmental factors such as air turbulence, temperature variation and vibration ect., it is difficult to obtain the test results reliably and repeatedly. Online or offline vertical test towers are commonly applied in many countries. A vertical test tower used online was designed in our workshop for testing an aspherical mirror Φ1.07 m, F/1.5.In order to fit for adjusting all freedom, a four-dimensional and another two five-dimensional adjustable tables are designed to adjust a mirror, a null lens and an interferometer. In our jobs, the stress, the deformation and the vibration modules of the tower are formatted by finite element methods to avoid resonance. After our works, the stable interferograms and testing repeatability are got by the test tower in the process of manufacturing aspherical mirror Φ1.07 m, F/1.5. The test result for nearly finishing is PV=0.313λ and RMS=0.024λ.