Abstract: Diurnal variations of photosynthetic and transpiration rate and the relevant environment factors of four kinds of sandy plants (Agriophyllum arenarium, Sophora alopecuroides, Artemisia ordosica, Salix psammophila), with leaves connecting the body were measured with portable Li-6400 photosynthetic measure system under natural conditions in the experiment area of the north in Hobq desert in Inner Mongolia. The results showed: The net photosynthetic of A. arenarium and S. psammophila was higher, it showed that they had a higher photosynthetic ability. The resistance ability of A. arenarium to the high temperature and low humidity or strong light was more strong than the other three plants. The relation between the open degree of stomatal conductance and humidity was closer, and vapor pressure deficit was the main factor of the change of stomatal conductance. Four plants had significant midday depression. Transpiration rate of A. arenarium was higher than the other three plants, so it belonged to high transpire plants. S. alopecuroides had low water use efficiency, A, ordosica and S. psammophila had high water use efficiency, and A. arenarium was between them. A. ordosica and S. psammophila had higher productivity in the region. The reaction of A. ordosica to dry environment was more sensitive than the other three plants.