Abstract: Computed Laminography (CL) has a unique advantage over CT for flat objects. However, the rotational CL does not satisfy the conditions of the filtered back-projection (FBP) reconstruction algorithm. This paper proposes a novel FBP reconstruction algorithm based on projection transformation for the rotational cone-beam CL. Firstly, the structure of the rotational CL is introduced; Secondly, the way generating projections and the method rearranging the data are elaborated; Lastly, the data rearranged is applied to filter and back projection, and the simulations of reconstruction prove that the method of this paper is effective.