Protective restoration is a conservation method based on analysis of painting materials and approaches to restoration. A Qing Dynasty export painting was used as an example to test this approach to the conservation and restoration of ancient Chinese oil paintings in a systematic scientific way. The project was discussed in terms of analytical requirements and restoration plans. X-ray fluorescence spectrometery (XRF) , digital microscopy and UV fluorescence spectroscopy were used together with chemical tests to characterize the painting materials and the composition of surface stains and black and brown spots on the oil painting. The analytical results show that the black and brown spots have high iron content, which suggests that they might be rust from the iron in the tin plate. In this case, the main goal is the restoration and protection after rust cleaning.