Under certain conditions, light wave propagation through atmospheric turbulence can cause presence of branch points. The number of branch points in the turbulence-distorted optical field is related with the strength of atmospheric turbulence, propagation range and the wavelength of laser propagated. The phase of compensating main laser is acquired from the distorted field of beacon. But the phase of the beacon is composed of the continuous phase and discontinuous phase when there are branch points in distorted field. The discontinuous phase is related to the number and location of branch points in distorted field, and the wavelength of main laser is always different from the wavelength of the beacon. Therefore, when the wavelength of main laser propagated is determined, the wavelength of beacon must be chosen so that the turbulence-compensated power of adaptive optical system can be improved after the branch-point considered in strong scintillation. The calculated results show that the compensation effect of adaptive optical system can be slightly improved when the branch points in turbulence-distorted optical field are considered, but the correction result of adaptive optics and become much better when the beacon wavelength chosen approaches the wavelength of main laser