Shaanxi Hanzhong Shimen is a mountain tunnel used for transportation in ancient my country. Its inner wall width and height are both more than 4 meters. In the Han Dynasty, the width of a track was only 1.5 meters, which shows that two cars could be accommodated in the Shimen. The "Shimen Inscription" of the Northern Wei Dynasty says: "" There are chariots and chariots in the Qiong Tower and the high pavilion. …Thousands of years have failed, and hundreds of vehicles have been replaced." It faithfully depicts the grand opening of Shimen to traffic. In the fourth year of Yongping in the Eastern Han Dynasty (AD 61), Emperor Ming ordered the construction of Shimen. From the search of existing historical materials, it is known that it is the earliest in ancient my country. A tunnel for pedestrians and vehicles. At that time, there was no explosives used in the construction of the Shimen Tunnel. The method of digging was to use the fire-water excitation method, that is, the rock mass was first calcined with fire and then quenched with water. The principle of thermal expansion and contraction was used to make the mountain. The broken rock and excavation are enough to show the wisdom of the ancient working people. The entrance of the Baoxie Valley in Hanzhong is the most dangerous pass on the Baoxie Road. The cliffs are steep and the water on the cliff is very fast. It is difficult to build a plank road during the Yongping period of the Eastern Han Dynasty. It took six years to dig a tunnel through the mountain. It was called "Shimen" in ancient times. Later, the Shimen Road was destroyed, and Yang Zhi, the governor of Liang and Qin states in the Northern Wei Dynasty, rebuilt the Baoxie Road. The "Shimen Inscription" was written to commemorate this incident. It is a famous cliff carving. "Shimen Inscription" is a representative of the cliff carvings of the Northern Wei Dynasty and a milestone in the development history of Chinese calligraphy. Because the cliff surface is vast and free from the limitations of paper, the calligraphy is profound, the brush strokes are strict, and the calligraphy style is majestic. It is naturally open, majestic and interesting, showing the masculine beauty of being simple and uncarved. This cliff carving is now part of the Shaanxi Hanzhong Museum.