Abstract: Two tomato cultivars with different Ca efficiency were used to study the kinetic characteristics of Ca2+ absorption rate, Ca accumulation and distribution in plant under Ca stress in tomato seedlings. The anatomical structure of stem was also studied at the same time. Results showed that there was a genotype difference in absorption of Ca between the different Ca efficiency tomato cultivars. The Ca2+ absorption rate of Cainefficiency cultivar 04 was higher than that of the Cainefficiency cultivar 05 under both sufficient Ca treatment (CK) and Ca deficiency treatment (Ca). In normal Ca supply condition (CK), Cainefficiency cultivar 04 had higher growth rate, Ca absorption rate and Ca content in seedlings than cultivar 05 while these indices were lower than those of 05 under Ca deficient condition. The ratio of R/S increased under Ca deficiency stress in both cultivars and the degree of the increase in 05 was larger than that in 04. In control the shape and size of epidermal cells and cambial cells of the young stem were uniform and the cells were regularly arranged and the xylem pipes of cultivar 04 were larger and more than that of 05. In the condition of Ca deficiency the development of these cells was affected significantly especially for Cainefficient cultivar which indicated that it was influenced greatly more than Caefficient cultivar when suffered by the Ca stress.