Abstract: The acquisition and maintenance of desiccation tolerance is related to the type of seed. Orthodox seeds are tolerant to desiccation while recalcitrant seeds are highly sensitive to desiccation. The desiccation tolerance changes during development of the orthodox seeds.Embryos becomes more tolerant as seeds mature and less tolerant as seeds germinate. The protective substances, such as sugars, LEA proteins and antioxidant defensive systems, are accumulated in orthodox seeds when the tolerance is acquired. The desiccation tolerance of seeds is of a complex and multifaceted properties, any one mechanism can't adequately explain the desiccation tolerance. Many protective substances cooperate with each other to modulate the desiccation tolerance. This report summed up the research advances on relationship between desiccation tolerance and protective substance s in recent years.