This work presents results on charged state topology of relativistic fragmentation of 6 Li and 7 Li nuclei at 4.5A and 3.8A GeV/c, respectively, on photoemulsion nuclei. The results would make it possible to answer some topical questions concerning the cluster structure of lithium isotopes. The isotopic composition of fragments and the channels of 6,7 Li fragmentation as well as the mean momenta ρβc of projectile fragments have been measured. Yields of 1 H (3 He ) appear to have the highest probability due to the fragmentation of 7 Li , while 2 H (4 He ) and 1 H (4 He ) are dominant through 6 Li -fragmentation process. The presence of exotic 6 He among fragmentation process is observed in 7 Li with yield 3% while 0.65% were found in 6 Li .