Forward degenerate four-wave mixing (DFWM) by using self-stability spilt-beam system has been demonstrated in iodine vapor. It is found that there is no laser-induced fluorescence (LIF) existing because of collision quenching at atmospheric pressure and room temperature, however strong DFWM spectroscopy of iodine vapor can be obtained. DFWM spectrum (554～556 nm) of iodine vapor has been measured by forward geometry of DFWM at atmospheric pressure and room temperature. This technique without suffering severe quenching problems at atmospheric pressure and room temperature is of importance to trace atom, molecular and radical in combustion diagnosis.