UHV power grid is one of the core developments of the global energy internet. The biological effects of power frequency electromagnetic field generated by the power grid has become the focus of social concern. Taking the field crops maize as the research object

we regularly measured the maize power frequency electric field exposure

and set exposure to three groups（2 kV/m

10 kV/m

and 15 kV/m） and a control group（background field

0）

namely

morphological index of maize

nutrients

protection enzyme live

and log rank sum test. Moreover

the data were analyzed by AVONA test. The results showed that there was no significant difference in plant height and stem diameter between the exposed group and the control group. There was no significant difference in the total functional leaf number and chlorophyll content

and there was no significant difference in the dry matter and grain weight of maize. Maize total protein content was relatively stable during the whole growth period

and soluble sugar or free amino acid content was not significantly decreased. But the soluble sugar and amino acid were different between the exposed group and the control group in different growth stages

and there was no consistent relationship by the electric field strength. No superoxide dismutase（SOD）

peroxidase（POD）

catalase（CAT）

glutathione S-transferase（GST） of four kinds of protective enzymes were significantly increased. But 4 kinds of protective enzyme activities were different between the exposed group and control group in different growth stages

and were not related with the electric field strength. Thus conclusions can be drawn that the 2 kV/m

10 kV/m

and 15 kV/m power frequency electric field exposures on maize amino acid

soluble sugar

4 kinds of protective enzymes have disturbance and physical function

and do not affect the maize photosynthesis and growth and yield.