To study the relative spreading of truncated Gaussian Shell-model (GSM) beam propagating through non-Kolmogorov turbulence, the extended Huygens-Fresnel principle and integral transform technique are used to derive the expressions for the mean-squared width and relative width of truncated GSM beam propagating through non-Kolmogorov turbulence. The variation of the mean-squared width and relative width versus waist width w0, coherence parameter α , truncation parameter δ and generalized exponent parameter γ are analyzed numerically. The results show the beam spreading is less affected by turbulence with the smaller α and δ , and the influence of non-Kolmogorov turbulence on beam spreading increases first and then decreases due to increasing waist width w0 and γ . The results obtained above are explained physically.