Abstract: In order to use the flotation device reasonably in the product integration and the test of the space mechanism, the bearing characteristics of a floating lockpin type flexible flotation device are tested by using a stiffness test bed under an analog loading. The results show that the bearing characteristics of the flotation device can be approximated by a linear spring compression model for the flotation device not being pre-compressed. When the flotation device is pre-compressed, the bearing characteristics of the flotation device can be approximated by a rigid body in the initial stage. As the bearing capacity exceeds the holding force of the flotation device, the bearing characteristics of the flotation device can be approximated by a linear spring compression model. In order to avoid the serious influence of the change of force and displacement in the loading process of the flotation device on the motion characteristics and the system performance of the space mechanism, the spring pre-compression of the flotation device should be adjusted according to the gravity product before the flotation device is used. In addition, the manufacturing errors of four groups of adjustable spring support assemblies should be strictly controlled. Moreover, the product should be constrained by using a release mechanism or a rigid support device before the gravity of the product is completely balanced.