Based on the theory that the intense electric field beneath a thunderstorm can produce corona discharge at the tip of a grounded metal point, a corona current measuring instrument was developed. Using wireless data transmission technology, the multistation wireless networking observation of corona current was conducted. The results of field experiments show that the corona current network observation system can operate normally in a certain region. The records of the corona current and synchronous environmental electric field were also analyzed in detail. The threshold values of the positive/negative environmental electric field for initiation of corona current were obtained, and the relation between corona current and environmental electric field were determined. The analysis results indicate that the intensity of the environmental electric field can be retrieved factually and accurately from corona current measurements.