Abstract: Static load tests were carried out on three types of lightweight composite slab units with different inner packing structures. The composite slab unit consists of a thin-walled steel framework filled with steel rebars/wire mesh reinforced ceramsite concrete. These units can be assembled to form a new type of lightweight prefabricated floor slab. The test results showed that the composite slab unit exhibitsed significant bearing capacity and deformation capacity. When specimens exhibited through cracking at the concrete bottom， severe buckling of thin-walled steel members， and crushing of the support-end concrete， with the vertical displacement of specimens reaching L/45 （L = span length）， the concrete filled in the thin-walled steel framework was not pushed out by the concentrated load acting on the center of the grid； the bearing capacity of the composite slab unit was improved by properly arranging the steel rebars and laying the steel wire mesh in the area grid； increasing the reinforcement ratio in the area of the composite slab unit not only improved the overall elastic stiffness but also enhanced the deformation capacity of the specimens； the increase of the ultimate load of the composite slab unit was greater than the increase of the elastic stiffness when the steel wire mesh was arranged in the framework area of the specimens.