To deal with the vibration and turbulence due to the long optical paths in extra-large concave aspheric mirrors testing,the dynamic interferometer associated with compensators is advanced.The difficulties in large concave aspheric mirrors testing are studied in this paper.Dynamic interferometer is employed to deal with vibration and air turbulence.Using the optical design software Zemax,compensators with 3.5 m aperture are designed as an example for concave aspheric mirror testing.Tolerance analysis indicates that the precision of this testing method is better than λ/90.