Abstract: The impact of motor vehicle noise on pedestrians in urban tunnel is studied by arranging eight equal spacing measuring points, at the interior, mouth, and exterior of Dongshan tunnel. The equivalent sound pressure level and spectrum of traffic noise within 20 min and the instantaneous sound pressure level and spectrum of traffic noise within 3 s when vehicles pass by pedestrians are measured by RTA840 dual channel real-time analyzer. The following measurement results are: (1) the equivalent sound pressure level of traffic noise inside the tunnel is 82 dB(A), which is 10 dB(A) higher than that outside the tunnel; (2) The spectrum characteristics of traffic noise outside tunnel and at the interior, mouth and exterior of the tunnel are the same, and the sound pressure level is high and the spectrum distribution curve is in the shape of "M" in the frequency band of 20~2 000 Hz; (3) When vehicles pass by pedestrians in the tunnel, the instantaneous sound pressure level of traffic noise reaches 86 dB(A), and compared with the background noise spectrum, the instantaneous noise spectrum levels are significantly increased in the frequency band of 20~8 000 Hz. Finally, combined with the test results and the actual situation of Dongshan tunnel, the traffic noise improvement measures for the acoustic environment in the tunnel are summarized from three aspects: sound absorption, sound insulation and management.