Transformation and high efficiency expression of key enzymes gene of C
4 photosynthetic characteristics are the important approach to improve photosynthetic efficiency and seed yield for C
3 crop wheat. Phosphoenolpyruvate carboxylase (PEPC) plays an important role in C
4 pathway. The authors have obtained several transgenic wheat lines with maize C
4 type PEPC gene. To explore the expression and functional characteristics of PEPC gene in transgenic wheat plants, PCR test, PEPC activity, gas exchange parameters, chlorophyll fluorescence parameters and yield related characteristics of transgenic wheat lines were determined, using untransformed wheat as the control, and the value of diurnal photosynthesis cumulative (VDPC) at the four stages and the correlations between net photosynthesis rate and stomata conductance, intercellular CO
2 concentration and transpiration rate were analyzed. The results showed that in the four determination stages, net photosynthetic rate of transgenic wheat obviously increased For instance VDPC was increased by 29.1% and 23.3% on the 15th day after anthesis. Stomatal conductance and transpiration rate in flag leaves of transgenic wheat obviously increased compared to the control, and intercellular CO
2 concentration decreased. Net photosynthetic rate of transgenic wheat enhanced by 23.2%, and variation scope of
Fv/Fm,
qp, NPQ, and
ΦPSII of transgenic wheat was smaller than that of the control from 8:00 to 12:00 on the 15th day after
anthesis; the major yield characteristics, such as weight per stem, thousand grain weight, single spike weight and harvest index of transgenic wheat, were significantly higher than those of the control. The results described above indicated that the transgenic wheat expressing maize PEPC gene showed better photosynthetic characteristics than untransformed plant and has the potential to increase wheat yield.