The utility model provides an electricity quantity monitoring device of a machine room power cabinet. The electricity quantity monitoring device includes a man-machine interaction host, an electricity quantity collector, a mutual inductor plate, a current sampling connecting line, and a communication connecting line. The mutual inductor plate is connected with the electricity quantity collector via the current sampling connecting line. The electricity quantity collector is connected with the man-machine interaction host via the communication connecting line. The electricity quantity monitoring device can convert a high voltage or a big current into a standard small current in proportion, and then the electricity quantity collector carries out the electricity quantity collection, and next the collected data is transmitted to the man-machine interaction host, and a worker can check the data at any time. The man-machine interaction machine can dynamically display a visual data picture, so the friendliness of the device is greatly improved. At the same time, the mutual inductor plate can be used for separating a high voltage system to guarantee the safety of people and devices, and the installation of the mutual inductors becomes more convenient. Besides, the electricity quantity monitoring device is beautiful and is easy to maintain, and the device becomes more standard and smaller.