A load fuzzy modeling device for the power system based on the causality diagram, the composite cloud generator and the improved T-S fuzzy model, comprising: a hardware device, including: the sensors, a signal conditioning and filter module, an A/D conversion module, a causality conversion module, a DSP module, a memory module, a display and keyboard module connected with the DSP module, respectively and a communication module connected with the PC. The voltage and the current are respectively acquired from the system through a voltage transformer and a current transformer, and then are transmitted into the filter circuit for filtering, thus are amplified through a amplifier LM258P as the voltage within the range of −5V ˜+5V so as to input into the A/D conversion modules for sampling; the digital signal is simply processed by the causality conversion module according to certain analysis algorithm principle, and the processed signal is transmitted into the DSP to process, the final results thus displayed on the LCD screen and transmitted into the PC through the commutation module.