The invention discloses an afforestation method capable of preventing marine organisms from gnawing the base stem parts of pagatpat. In March and April every year, robust pagatpat nutrition bag seedlings are selected as afforestation materials in the sheltering and sunny exposure coastal beach with an appropriate amount of sludge, shallow water, small waves and low salinity, nutrition bags are peeled away before planting, planting is carried out after degradable plastic hoses split in the longitudinal straight line are arranged on the base stem parts of the pagatpat seedlings in a sleeving mode, a protection net is established around the afforestation land, and the damage of people and livestock to the afforestation land is avoided. By means of the afforestation method, shrimps, crabs and other marine organisms can be easily and effectively prevented from gnawing the base stem parts of the pagatpat, the afforestation survival rate and the preserving rate are increased, and the later growth and development of the seedlings are not affected. The adopted materials are easy to obtain, cost is low, pollution does not exist, the method is simple, operation is easy, the afforestation method is suitable for application and popularization, and good ecological benefits, social benefits and economic benefits are achieved.