Abstract: The characteristics of calcium absorption by peanut roots was inverstigated by using 45Ca trace technology, electron X-ray microanalysis and solution culture. It was found that calcium can be absorbed in either elongation zone or mature zone of peanut roots, of the total Ca uptake. 28.9% ~ 37.4% was attributed to elongation zone, and other (71.1%~65.3%) to mature zone. When solution Ca concentration ranged from 0~0.5 mmol/L, Ca uptake could completely mediated by metabolism, and the relationship between Ca2+ absorption rate and its concentration could be described by Michaelis-Menten dynamics model, where Km was 0. 0549mmol/L and Fmax was 3.81nmol/(cm.h) Nonmetabollc effect of Ca absorption appeared or increased with the increase of Ca2+ concentration. When solution Ca concentration was 2.0mmol/L, 63. 2% of Ca uptake was metabolically mediated, and 36. 8% was mediated by nonmetabolic factors.