Abstract: The purse seine and cage culture are primary inner lake pollutant sources in Jianghan Plain.  After the implementing of the action of “purse seine demolition of lakes and reservoirs” in Hubei Province, it is quite necessarily to discuss and evaluate the effectiveness of the lake seine demolition and its ecological environment benefits. Therefore, a method was realized to rapidly monitor the effect of purse seine demolition, based on the modified normalized difference water index (MNDWIn), texture analysis, et al., taking the Honghu Lake, the largest lake in Hubei Province, as a case. Based on the monitored area changes information of purse seine, the environmental benefits of demolition were estimated, according to the pollutant share ratio of aquaculture type in the Honghu Lake and the production and discharge coefficient method. The results showed that: (1) Due to the action of “purse seine demolition”, the purse seines in the Honghu Lake have been completely removed. The area of purse seine culture has been removed by 117.81 km2, and the natural water surface area has increased by 110.49 km2. The coastal landscape of the Honghu Lake has greatly improved. The effect of demolition was most significant especially in the western and northern regions. However, there were still some non-water substances need to be cleaned in the north and south of the Honghu Lake. (2) The pollutants that discharged into the lake were reduced by 1 265 284.38 kg, in which the concentrations of total nitrogen and total phosphorus nutrients were reduced by 0.848 mg/L and 0.185 mg/L respectively. The water quality levels of these two indicators would be raised up to Class II from Class III before demolition, if there is not any other new pollutant source added. So, the eutrophication pollution of the Honghu Lake would also be greatly decreased. The study provides a rapid monitoring method to evaluate the effect of the implementations of the action of “purse seine demolition of lakes and reservoirs”, which can be applied to regional lake management and watershed ecological environment protection.