The invention discloses a method for early warning thunder and lightning on the basis of automatic tracking of atmospheric electric field background noise. The method mainly comprises steps as follows: S1: actually measured atmospheric electric field data of a watched area are input; S2: input data are intercepted at equal time intervals and framing processing is performed; S3: the power spectrum of the atmospheric electric field in each time period is solved with frame as a unit; S4: the ratio of atmospheric electric field power of each frame to background noise power is calculated for early warning of thunder and lightning. By means of the method, the background electric field changing slowly at the non-thunderstorm moment can be automatically tracked, influence of noise on judgment of sudden change of the electric field at the earlier stage of thunderstorm is eliminated, and a high-adaptability and high-practicability thunder and lightning early warning method is provided for areas with complicated electric fields and larger climate differences.