Abstract: A simple evaluation criterion was established to compare the influence of dosage of oiliness agents，antirust agent and emulsified oil on the stability of emulsion prepared with fresh water, deionized water, or water placed for a long time. It is found that for the poor stable emulsified oil with more interference components, the emulsion prepared with the long placed water containing more impurities is more stable than the one prepared with other two waters. However, for the emulsified oil with optimized formula and with less interference impurities, the more clean water used, the more stable emulsion is. Formula optimization for emulsified oil is not only beneficial to strengthen the stability of the emulsion and can improve its lubricity and extreme pressure properties.