The characteristic changes of mucilaginous seed coat before and after wetting were observed by dissecting microscope and scanning electron microscopy. The effects of seed coat ornamentation and mucilage on water uptake，sand adhesion，floatability and germination of seeds were analyzed. The result showed that: (1) The seed coat ornamentation of Peganum multisectum was formed by outward protruding appendages on the outer periclinal walls of epidermal cells and presented a reticular structure. Pellicles covered on the polyhedral meshes of seed coat ornamentation, making the meshes form closed chambers. After absorbing water，the pellicles became mucilaginous and a lot of bubbles appeared in the mucilage chambers. The mucilage was gradually dissolved and disappeared after water absorptiondehydration. (2) The mucilage layer and chambers of seed can store much air，which facilitated seed floatation on moving water and further dispersal. Meanwhile，seed coat ornamentation and mucilage can enhance adhesive ability of seed to the soil and other plants，thereby escaping from seeds bareness to maintain seed vigor. The seed coat ornamentation and mucilage also can absorb a large amount of water quickly and hold water，thus maintaining soil seed bank in the harsh desert. (3) The mucilaginous seed coat can delay germination but promote seedlings growth in an unpredictable environment，which increasing the ability of plant establishment.