A nano-scale p-n junction diode is set up for photovoltaic response simulation, and the codes are based on Matlab® environment. The continuity and transport equations for electrons and holes are installed in the program and proper boundary conditions are used. The surface recombination velocity is found to be an influential parameter for the short-circuit current under regular AM1.5 solar excitation. From the simulation, a 35% degradation on Jsc can be expected in the nano-scale device when the surface recombination velocity increases from almost zero to 107 m/s. Meanwhile the reduction of the minority carrier lifetime is not as detrimental as the surface recombination towards the nano-scale photovoltaic device.