We developed a 1-D model (the PLC-P model) for modeling canopy reflectance over sloping terrain. The effects of sloping terrain on single-order and diffuse scattering are accounted for by path length correction (PLC) and the P theory, respectively. Currently, we have developed the prototype of PLC-P model, in which only the sloping effects on the single-order are accounted for through path length correction. This first version of PLC-P model is called PLC model. The PLC model was validated via Monte Carlo simulations. The comparison with the Monte Carlo simulation revealed that the PLC model can capture the pattern of slope-induced reflectance distortion with high accuracy. The PLC-P model can provide a promising tool to improve the simulation of canopy reflectance and the retrieval of biophysical variables over mountainous regions.