We apply nondegenerate four-wave mixing processes to the generation of stable continuous variable entangled light and study the time evolution of continuous variable entangled light. We analytically get the characteristic function of the two-mode field and find that the system is an optical parametric amplifier. We also show that the two-mode cavity field exhibits stable continuous variable entanglement under certain conditions. The degree of entanglement depends upon the two-photon intensity I2，the cooperativity parameter C and the side-mode detuning Δ′.