Qingchun Road rivercrossing tunnel in Hangzhou is a huge project with largescale construction activities and complicated construction technologies. Due to the numerous uncertain factors, the project involves a large amount of risks. The paper analyzes on the difficulties and risks of unexpected incidents that may occur during the construction of the project under the special geological conditions under Qiantang River and the constraints of the surrounding external environments. Furthermore, the paper studies on the effects of the risk factors on the safety and quality targets set for the project by means of disaster risk evaluation matrix method (R=P C) , by which qualitative evaluations and quantitative analysis are provided. Finally, on basis of the analysis results, the article recommends some countermeasures for the risks. The article can provide basis for further discussions on the fullcourse control of the risks of huge and complicated rivercrossing tunnels.