Diesel Particulate filter (DPF) is installed as after treatment device of exhaust gas in diesel engine, and it collects Particulate Matter (PM). However, as the operation time of engine increases, the PM is accumulated in the DPF, resulting in deterioration of PM collection efficiency and increase in pressure loss. Therefore, Post injection has been attracted attention as the DPF regeneration method for burning and removing PM in the DPF. But, Post injection causes oil dilution when fuel is injected at the middle to late stage of expansion stroke. Oil dilution are concern to decrease the stroke lubricity of piston movement and the thermal efficiency. In order to estimate deposition amount of fuel spray that influences oil film, we should elucidate spray impingement behavior on wall surface of oil film, to research more from the behavior of in-cylinder spray during post injection. In this study, we aimed to construct CFD that predicts oil dilution which is concern for post injection in diesel engine, with high accuracy. In this report, we constructed Double Laser induced fluorescence (LIF) Method applying LIF Method. In the Double LIF Method, different fluorescent agents were added to diesel oil and engine oil, and UV-LED was used as excitation light. Each fluorescence wavelength was spectrally separated at a specific wavelength, and Double LIF Method makes it possible to simultaneously measure deposition amount of diesel spray impinging for oil wall and oil film thickness. As the result of measurement using Double LIF Method, it was found that a large difference of amount deposition of fuel spray impinging on dry wall and oil film. Due to influence of oil film, deposition area and deposition amount decreases compared with dry wall.