Abstract:Take the capsizing accident of cruise ship “Oriental Star” as an example. The analysis of the previous study and the field investigation shows that on 1 June 2015, from 21:00 BT to 21:15 BT, severe weather such as thunderstorms, strong winds, heavy rains and tornadoes hit the investigation area. The duration was about 30 minutes. The disaster process was characterized by the most severe windstorms, with spatial discontinuities and small scales. The survey results show that there were vertical shear and horizontal shear in the wind field along the Yangtze River in the accident area. Radar monitoring showed that the mesocyclone moved from the west bank of the Yangtze River to the east bank, having vortex cha-racteristics. This process was mainly based on windstorms. The severely affected area was concentrated within the range 8 km north of the accident, the Sitai village on the east bank of the Yangtze River, which is about 4 km away from the accident, was the most seriously affected, This region had strong wind shear and signs of divergence.The main affected objects were trees, crops, houses, boats, etc., causing the most damage to trees, a total of 31 disaster sites, accounting for 72.1% of the total survey sites. In the accident area, the trees on the west bank of the Yangtze River were broken or the direction of lodging was mainly southeastward, the trees on the east bank was mainly eastward. So, the direction of the trees dumping was clearly consistent. However, there were horizontal shears on both sides of the Yangtze Ri-ver, and the wind direction was deflected by nearly 90°. The quantitative evaluation method of wind disaster was explored by combining actual disaster with mechanical model. Take the severely affected poplar as an example, the anti-overturning moment calculation method was used to estimate the disaster rate. The results show that strong wind was one of the important causes of the accident. The wind speed of the di-saster was 28.7 m·s-1, reaching Grade 10 or above.