A highly sensitive noncryogenic rubidium magnetometer based on spin exchange relaxation free (SERF) is designed, whose sensitivity at 15 Hz is 6 fT/ Hz. With this SERF magnetometer, the difference in the human brain magnetic field induced by eye opening and closing is recorded inside the shielded barrel. This SERF magnetometer is operated in double light mode with a pump-probe arrangement. Compared with single beam arrangement, this SERF magnetometer can achieve a higher sensitivity and does not require any extra magnetic modulation. Thus, the complexity of the acquisition system is reduced and the lock-in amplifier is not needed any more. Moreover, this kind of configuration is easily adapted to miniaturize the sensor array for the future whole-head magnetoencephalography equipment.