Considering the perturbation, the results of theoretical calculation of five Rydberg series energy levels 6s2ns2S1/2(n=7-20),6s2nd2D3/2(n6-20),6s2nd2D5/2(n=6-20),6s2np2P^(0)_(1/2)(n=7-20), and 6s2np2P^(0)_(3/2)(n7-20) for Tl I are presented using th