In order to probe the relationship between calcium content and its status in fetal tissue and minor's calcium deficiency, the calcium content of seven tissues of fetus aged 4 to 10 month was measured and analyzed. Results showed that the calcium content in fetal tissues was an unstable variable, and it was a function of spatio-temporal factors. Calcium content in fetal tissues reduced with the increase of age and weight of tissue, making a continuous decrease of the calcium content in per gram tissue. This characteristic could last to about the age of 20 years old of children. The physiological character that calcium content in tissues of fetus and minor decreases with the development can make people to be more aware to calcium deficiency, laying the physiological basis of calcium deficiency of the people in low age, providing the physiological information for adjusting and controlling the calcium nutrition of the fetus, minor and pregnant woman.