The study of measurement methods for strong electric fields in small spaces is a challenge. By utilizing the Stark effect of spectral lines and selecting reasonable atoms or ions, measurements can be completed without interference. This article designs a set of atmospheric pressure nanosecond pulse discharge experimental device, which generates a strong electric field through needle electrode discharge, and tests the splitting of He 447.1nm spectral lines under strong electric fields generated at different discharge voltages. When the spectral line broadening is difficult to obtain directly by observing the spectral line, by using the non-linear least squares, the allowable component, the prohibited component and the field independent component of the spectral line are analyzed and the corresponding wavelength offset is calculated to obtain the electric field size. According to Mason’s formula, based on energy equivalence, the experimental results meet theoretical expectations, and this method can be used to measure strong electric fields in small spaces. Analysis indicates that the discrepancy between theoretical and experimental results may be attributed to the shielding effect caused by the plasma produced when helium gas undergoes breakdown.