Selective Laser Melting (SLM) is a common additive manufacturing technique which uses a scanning laser source to fuse metal powder layer by layer. Although complex geometries can be produced, quality and repeatability of parts are still two challenges due to complex physical transformations of the metal powder and highly dynamic temperature fields. Finite Element Models (FEMs) have been developed by researchers in order to predict melt pool behaviors. However, simulations on FEM software are too computationally intensive for real-time control applications. Thus, there arises the need for a control-oriented model of SLM processes. In this paper, a state-space control-oriented layer-to-layer model based on the general heat conduction equation is developed. The layer-to-layer model is constructed to step from one layer's thermal feature measurement to the next, thus reducing computational complexity to a level suitable for control. To validate the model, an experiment of a rectangular thin part was conducted, and the simulation described the experimental thermal measurements with 5% error in the output.