In this paper, we consider a class of nonlinear fractional differential equations involving the Riemann-Liouville fractional derivative with infinite-point integral boundary conditions. Our analysis relies on the fixed point index theory and u 0 -positive operator. An example is given for the illustration of the main work. c 2017 All rights reserved.Keywords: Fractional differential equations, infinite-point integral boundary condition, u 0 -positive operator, fixed point index theory. 2010 MSC: 26A33, 34A34.