Abstract: This paper introduces the process of multiple fields tripping of a low-low temperature electrostatic precipitator (LLT-ESP) in a 600MW unit and the checking and analyzing process of its cause, by analyzing the damaged condition of support insulator and the shaft insulator of the tripping electric fields, it is pointed out that multiple electric fields tripping is the result of the combined action of insulator pollution, dew, surface creepage and temperature decline by rain and snow, and in order to reduce the risk of the LLT-ESP’s electric fields trip , it is necessary to reduce ammonia escape, clean insulators in time, moderately raise the heating temperature of insulators and add thermal insulating layer to the the uninsulated parts of the big incubator .