We study forward self-similar solutions to the 3-D Navier-Stokes equations with the fractional diffusion (−∆) α . First, we construct a global-time forward self-similar solutions to the fractional Navier-Stokes equations with 5/6 < α ≤ 1 for arbitrarily large self-similar initial data by making use of the so called blow-up argument. Moreover, we prove that this solution is smooth in R 3 × (0, +∞). In particular, when α = 1, we prove that the solution constructed by Korobkov-Tsai [23, Anal. PDE 9 (2016), 1811-1827 satisfies the decay estimate by establishing regularity of solution for the corresponding elliptic system, which implies this solution has the same properties as a solution which was constructed in [17, Jia andŠverák, Invent. Math. 196 (2014), 233-265]. n 2 , γ(r) = +∞ 0 s r−1 e −s ds, r > 0.