The quarantine procedures for introducing seeds, seedlings and propagating materials from abroad or regions are introduction approval, introduction quarantine and isolated trial planting. This procedure has two characteristics in Beijing: first, two-level quarantine institutions, external inspection and internal inspection, have the same approval, and only external inspection is responsible for quarantine. The external inspection and internal inspection * * * two-level quarantine institutions shall supervise and isolate the trial planting. Second, scientific research, teaching and other units should collect and introduce a small amount of germplasm resources from all over the world, but there are many kinds, keep them in Beijing, and then transport them to various provinces and cities for trial planting, including planting in Beijing. These two characteristics of external introduction work constitute the complexity of quarantine in our city. Only by strictly implementing the quarantine procedures can we straighten out the contradictions in quarantine work, avoid missing inspection, prevent the introduction, expansion and spread of dangerous pests and ensure the safety of agricultural production.