Abstract: The aerated rate of seal materials makes an important effect on the micro-environment and plantlets of tissue culture. It is an important parameter for evaluation and selection of seal materials, and is a basic datum for the automatic and precise control of micro-environment. To solve the problems of caculation and measurement of aerated rate, arithmetic method based on mathematics and statistics principle was set up, and apparatus and procedures for measurement accordingly were developed. Finally, the aerated rates of the permeable paper, four-layer-sulphated paper and the low density polythene film were measured as 1.551 h^-1, 0.408 h^-1 and 0.302 h^-1, respectively.