This paper is devoted to the analysis of blow-up solutions for the fractional nonlinear Schrödinger equation with combined power-type nonlinearities2s . Firstly, we obtain some sufficient conditions about existence of blow-up solutions, and then derive some sharp thresholds of blow-up and global existence by constructing some new estimates. Moreover, we find the sharp threshold mass of blowup and global existence in the case 0 < p 1 < 2s N and p 2 = 2s N . Finally, we investigate the dynamical properties of blow-up solutions, including L 2 -concentration, blow-up rate and limiting profile. Keywords: The fractional Schrödinger equation; Blow-up solutions; Combined powertype nonlinearities; Sharp thresholds; The dynamical behavior where 0 < s < 1, f (u) = |u| 2p u. The fractional differential operator (−∆) s is defined by (−∆) s u = F −1 [|ξ| 2s F(u)], where F and F −1 are the Fourier transform and inverse Fourier transform, respectively.