According to statistical results, the takeoff and landing phases are the accidentprone phases of the whole flight mission although they take up very short proportion of the total flight time. In recent years, incidents and accidents of overrun or deviation from runway have occurred several times while takeoff and landing on the contaminated surface. Wet and contaminated runway should be responsible for these accidents. In order to keep the aircraft safety, the flight performance on a contaminated runway should be determined. Contaminates induce additional drag for aircraft operating on contaminated runways, which make great influence on the takeoff and landing performance. The mechanism of water spray pattern caused by tires is analyzed, the calculation and assessment methods of additional drag on standing water contaminated runway are researched. Example indicates that the standing water addition drag is basically proportional to water depth and aircraft ground speed’s square. The tendency and magnitude of calculation results are credible, and the method is accurate enough to be applied to engineering assessments.