We demonstrate the stabilization of optical frequency combs (OFCs) using a segment of fiber delay line as reference. An Er-doped fiber mode-locked laser is phase locked to a kilometer-long fiber delay line using three different schemes. The short-term stability of the comb modes in the OFC stabilized by these schemes are obviously enhanced, down to 10<sup>-12</sup> level at millisecond average time. Among these three schemes, phase locking two bunches of comb modes in the OFC to the same fiber delay line exhibits the lowest residual phase noise. Fiber-delay-line-referenced optical frequency combs can provide reliable laser sources in precise metrology owing to its advances of low-cost, compactness and highly-integration.