Suppose r ≥ 2 is a real number. A proper r-flow of a directed multi-graph G=(V,E) is a mapping f:E→R such that (i) for every edge e ∈ E ,1 ≤|f(e)| ≤r-1; (ii) for every vertex v ∈V,Σe ∈ E +(v)f(e) =0. The circular flow number of a graph G is the least r for which an orientation of G admits a proper r-flow. The well-known 5-flow conjecture is equivalent to the statement that every bridgeless graph has circular flow number at most 5. In this paper, we prove that for any rational number r between 2 and 5, there exists a graph G with circular flow number r.