In order to find out the effects of microgravity on the distribution of Ca2+ in asparagus seedlings, tropic reaction of rhizome, the response of cells and organizations, as well as the distribution and transportation in organization under simulated microgravity condition were observed by means of 45CaCl2 labelled autoradiography. The results showed that the distribution of calcium cations highly correlated with gravity. The absorption, distribution and transportation of calcium were greatly affected by gravity.