Under the background of global climate change, screening urban greening plants with strong drought tolerance is an important way to deal with the shortage of groundwater resources and urban greening construction in the future. In this paper, Camellia japonica and Rhododendron hybridum were used as materials, and the drought resistance of petals and leaf tissues of them during water stress were compared. The embolism vulnerability curves of petals and leaves were constructed by optical technology, and the morphological and structural characteristics of petals and leaves in C. japonica and R. hybridum were observed. The results showed that: (1) there was no significant difference in the water potential of the soil where C. japonica and R. hybridum were grown under natural drought, and both were significantly reduced from day 9 compared with the control. The water potential of R. hybridum leaves and petals decreased significantly on day 9 after the natural drought, while the water potential of the leaves and petals of the C. japonica leaves decreased significantly when the natural drought lasted until day 12. (2) The P50 (the corresponding water potential when 50% embolism occurred) values of petals and leaves of R. hybridum were -3.24 MPa and -4.40 MPa, respectively, which were higher than those of C. japonica (-3.99 MPa for petals，and -5.92 MPa for leaves). (3) There was no significant difference in the thickness of petals and the thickness of upper and lower epitheliums between C. japonica and R. hybridum, while the veins density and stomatal density of C. japonica petals were significantly greater than those of R. hybridum; C. japonica leaves thickness, upper and lower epithelium thickness, sponge tissue thickness and leaf veins density were significantly greater than those of the R. hybridum. The embolism vulnerability of C. japonica and R. hybridum is related to its tissue morphological structure, the thicker the leaf thickness, the upper and lower epidermis thickness and the sponge tissue thickness, the less embolism vulnerability there is. In the case of increasing drought in the future, C. japonica can be preferentially selected as a flower plant for urban greening.