This paper studies the influence of the cross-Kerr(CK) coupling on the production of entanglement be- tween two movable mirrors in an optomechanical system formed by two movable mirrors. It finds the frequency range for generating the entanglement of two movable mirrors could be effectively extended by the CK coupling. In particular, the maximal entanglement of two movable mirrors can be increased by the CK nonlinear medium. Our results suggest that the CK nonlinear medium could be used to improve the entanglement of two oscillators in optomechanical systems which could be useful for generating mesoscopic entanglement in experiments.