The invention relates to a method for judging line insulation conditions, and belongs to the technical field of line insulation condition detection. The method provided by the invention comprises thefollowing steps: 1. establishing a line insulation condition data set based on current, power factors and time according to a line historical database; 2. collecting an actual insulation condition ofa line; 3. performing time correspondence on the actual insulation condition of the line with the data in the line insulation condition data set in the step 1, and establishing a corresponding relationship between the power factors and the insulation conditions; 4. establishing a line insulation condition feature library based on the line insulation conditions; 5. classifying the line insulation condition feature library; 6. collecting real-time operation data of the line; 7. incorporating the real-time operation data of the line into the line insulation condition data set; and 8. comparing the real-time operation data of the line with the data in the line insulation condition feature library to judge the present line insulation condition.