The invention relates to a noninvasive household load characteristic automatic extraction method and device. The method comprises the following steps that voltage and current are sampled at the electrical entrance of the monitored user household according to the set frequency and precision; a user household load switching operation event is monitored; the voltage and current sampling data before and after the effective switching event are intercepted; the load steady state and transient state characteristics are analyzed; and the load characteristic data are transmitted to the user side to perform information marking according to the specified format. Invasion of the user household is not required so that installation and reconstruction are facilitated. The load characteristic information is automatically extracted so that the effect efficiency can be enhanced and the error caused by manual operation can be avoided.