For complex large-scale systems with many electromagnetic interference measurement items, measurement points and measurement conditions, the traditional sweeping frequency-domain measurement method has practical problems such as high cost and long period. In this paper, a multi-channel time-domain fast measurement method for low-frequency electromagnetic interference is proposed, and a multi-channel time-domain low-frequency electromagnetic interference measurement system is developed. The experiment verify shows that the proposed measurement method and the developed measurement system can accurately obtain the low-frequency electromagnetic interference characteristics of complex large-scale systems, and the measurement speed is fast and the cost is low.