Abstract: In view of the advantages of non-intrusive and high spatial and temporal resolution, the electric field measurement method based on the electric-field induced second harmonic (E-FISH) effect has attracted wide attention in the fields of gas discharge and plasma diagnosis in recent years. Based on the spatial distribution characteristics of the fundamental frequency laser, the complete expression of the second harmonic intensity is theoretically deduced. Combined with the constructed electric field measurement platform based on the E-FISH effect, the effects of optical power and polarization direction of the fundamental frequency laser, electric field spatial distribution and the length of the action region, Rayleigh length and other factors on the intensity of the second harmonic are discussed, and the influence law of temperature and humidity on the intensity of the second harmonic is analyzed. Theoretically, the generated second harmonic hardly varies with humidity, whereas, the measured values may decrease with increasing humidity due to the scattering of the second harmonic by high humidity air. The temperature has less effect on the second harmonic intensity in the range of 20~30 ℃. Both theoretical and measured values increase slightly with the increase of temperature, and the increase of measured values is larger than the theoretical values.