Abstract: Most terrestrial plants, according to the method of atmospheric CO2 assimilation, can be divided into 3 types: C3, C4 and CAM plants. Because of the CO2 concentration mechanism, C4 plants exhibit higher photosynthetic efficiency than C3 plants. However, many important crops such as rice, wheat and soybean, are C3 plants. To improve the photosynthetic characteristics of C3 plants, researchers have tried to enhance the C4 photosynthetic capability to increase photosynthetic productivity in C3 plants. Important progress has been made in genetic engineering. This paper discusses the progress made in improving the fixation of atmospheric CO2 by transgenic approaches and problems that need to be addressed.