As we all know, water inrush and mud gushing is very common in broken rock tunnels under high water pressure. Water inrush and mud gushing often occurs under the action of seepage force because of high water pressure which can lead to the ground subsidence, cracking and the damage of tunnel structures. In this paper, the author takes the engineering practice for example to analyze the mechanism of water inrush and mud gushing under high water pressure and put forward appropriate treatment methods. According to numerous researches on water disasters, two main types of water inrush and mud gushing in broken rock tunnels are summarized: the partial cracking in the cross section and the longitudinal water inrush and landslide. This paper not only describe where and when these two types of water inrush and mud gushing will happen but also the different formation and mechanism of water inrush and mud gushing. In addition, prevention and treatment measures of water inrush and mud gushing are put forward. The multiple advanced geological detections combined by long-term and short-term forecasts are the fundamental measures that can effectively prevent the water inrush and mud gushing during the tunnel construction. Besides, the effective treatment measures are also summarized, including the advanced drainage and advanced grouting method. Advanced drainage is an effective method to relief energy of high water pressure, and advanced grouting can form a shelter that keep water outside by filling the fissures and cracks with grouting materials in the fracture zones.