Abstract:With the use of MODIS remote sensing image data, the algal bloom in Dianchi Lake is monitored by false colored synthesis and the Normalized Difference Vegetation Index(NDVI) vegetation exponential methods. According to the monitoring, the algal bloom in Dianchi Lake firstly occurred on May 7 and reached the highest point in July. Although in June, August and October it was not so serious, but its distribution was still much higher than in May. The distribution area of the algal bloom extended to Haikou and reached the far south of Dianchi Lake during its active bloom. The bulk algal bloom concentrated in the north and showed a characteristic of a higher distribution near the lake bank than in the center of lake, higher in the west bank than in the east and south banks. In conditions of enough nutrients, a high temperature plays a catalytic role, but it is not the determining factor of the algal bloom. Sufficient sunshine is necessary for the formation of the algal bloom. However, rainfall may change water temperature and sunshine conditions, therefore, it will inhibit the growth of the algal bloom. Gentle breeze (velocity less than 3 m/s) is good for its formation. While strong blast obviously limits the distribution of the algal bloom, especially when it is not so dense one.In short, meteorological conditions through interaction and working together affect the formation of the algal bloom.