Let p be a prime number. The Artin-Schreier-Witt tower delt in [DWX] is defined by a single variable polynomial f(x) ∈ Fp which is a tower of curves ⋅ ⋅ ⋅ → Cm → Cm-1 → ⋅ ⋅ ⋅ → C0 =A1 ,with total Galois group Zp . In [DWX], Davis, Wan and Xiao showed that when the conductor mχ of a character χ is large enough, the slopes of NP(f,χ)L form arithmetic progressions which are independent of mχ . We mainly studied its two generalizations.