The invention relates to a method for analyzing an active power and voltage calculation error of day-ahead planned power flow, which comprises the steps of acquiring a power flow deviation line, a voltage deviation bus and a power flow deviation generation load set; acquiring a deviation value of power equipment, and determining the sensitivity and the single time point error contribution degree of the power equipment for the power flow deviation line, or determining the sensitivity and the single time point error contribution degree of the power equipment for the voltage deviation bus; and the error contribution degree of 96 points all day of the power equipment for the power flow deviation line or the voltage deviation bus according to the single time point error construction degree. Themethod provided by the invention can realize automatic analysis for reasons of an active power and voltage calculation error of the planned power flow, quickly analyzes key factors influencing the rationality of a planned operating mode and provides a technical support for improving the rationality of scheduling data of the planned operating mode.