For Z-tilt and G-tilt, the variances of the arrival-of-angle fluctuations of optical wavefront, which are functions of the power-law exponent β and the generalized coherence length ρ0, are deduced by introducing the generalized phase spatial power spectrum for non-Kolmogorov turbulence respectively. The results show that for 2<β<4, the variances of the arrival-of-angle fluctuations of optical wavefront become larger and larger with the increasing of the power-law exponent β and the variance of G-tilt is smaller than that of Z-tilt for the same β.