[en] Cosmic-ray ionization in the lower atmosphere was measured by the pressurized ionization chamber on lakes with different altitude and latitude in Yunnan province and Xinjiang Autonomy Region and on a high-altitude ballon. The variation of cosmic-ray ionization with latitude was also measured from Hainandao island to Manzhouli. An expression for distribution of cosmic-ray ionization with altitude and latitude was given by: I(h, λm, Y) = (I0 + 0.0098λm) exp (7.27 x 10-5h1.184)I