In order to explore the fundamental relation and its corresponding functions between leakage current in insulators and its influential factors

we studied the relationship among leakage current Ih

relative humidity density Hr

equivalent salt deposit density ρESDD

and applied voltage U using the genetic algorithm（GA）. Firstly

artificial pollution tests were conducted on single suspension insulators; waveforms of leakage current were recorded and analyzed using a leakage current monitoring system. Secondly

the functional relationship among Hr

ρESDD

U

and Ih was obtained by GA. Finally

we compared this method with the least square method. The results show that Ih is related to ρESDD

Hr

and U in an order of influence from large to small. Compared with using the least square method to estimate the correlation coefficient between leakage current and the influencing factors

using GA can not only identify the functions connecting the factor

but also improve the accuracy of estimation. The simulation result shows that GA is effective and feasible to estimate leakage current. The research can be used as a reference for contamination degree estimation of insulators based on leakage current evaluation.