The invention relates to an instantaneously measured waveform-based nonlinear load electricity consumption characteristic analysis system and method. The method includes the following steps that: the 95% probability large value of the power supply fundamental waves of a nonlinear load and the 95% probability large values of harmonic waves at each order of the current of the nonlinear load are measured; power supply voltage real-time waveforms are reconstructed through using the 95% probability large value of the power supply fundamental waves; real-time current waveforms are reconstructed through using the 95% probability large values of the harmonic waves at each order of the current; and periodic sampling is performed on the constructed voltage real-time waveforms and real-time current waveforms, and the instantaneous impedance of each sampling point is calculated, and the nonlinear electricity consumption characteristics of the nonlinear load are obtained. According to the system and method of the invention, an electric energy quality or non-linear electricity consumption monitoring system is utilized to detect data in real time, so that timely analysis of the electricity consumption characteristics of the nonlinear load can be facilitated. The method of the invention has the advantages of simple steps and high universality. The non-linear electricity consumption characteristics obtained by using the method can be used repeatedly in various kinds of off-line analysis and calculation.