Permutation routing is a popular communication pattern in the interconnection networks. Most of previous works consider routings on Multistage Interconnection Networks (MINs) which consist of 2x2 switches. We considered all-optical rearrangeable permutation routing for Clos networks. The signal in the optical switch with the same wavelength will cause the crosstalk problem, so our proposed algorithm is to rearrange the same wavelength signals, so that no duplicate wavelength in any single middle switch. To avoid wavelength crosstalk, we use wavelength domain approach, and then to solve blocking condition by space domain approach.