Simultaneously improving the communication speed and equalizing the nonlinear frequency response are still challenging for tunnel visible light communication (TVLC) system. Here, we propose and numerically investigate a frequency domain pre-equalization scheme for discrete multitone (DMT) modulation TVLC system. The amplitude of each subscriber is appropriately pre-equalized by optimized nonlinear compensation parameters. Simulation results demonstrate that our proposed equalization technique can resist the channel attenuation of the signal high-frequency part and further flatten the nonlinear channel response. Without forward error correction technique, the bit error ratio (BER) performance can reach 7.66×10-6 in a 2.05 Gbit/s DMT-TVLC system.