Abstract: The article discusses seedlings pulling mechanism of the rice seedling trays according to the experimental researches on tensile strength of rice seedling and the ability of pulling seedling from trays, in order to provide some bases for designing the machines for pulling rice seedlings from trays. The results of the researches show the tensile strength of the rice seedlings increases when the age and the height of the seedlings increase, but it decreases when the location where seedlings are clipped rises, and the strength of pulling seedlings from trays is much affected by the humidity of the trays and little affected by the age of the seedlings; the strength decreases when the humidity of the trays increases and the pulling strength needed reached the least value when the relative humidity is between 40 percent and 60 percent, and under the normal condition, the tensile strength of the seedlings is much bigger than the strength of pulling seedlings from trays. Therefore, it is feasible to pull out the seedlings from the trays.