Bak P,Tang C and Wiesenfeld K enunciated the concept of Self-organized criticality(SOC)in his paper"Self-organized criticality:an explanation of 1/f noise?"published in "Physical Review Letters" in the 1980s. The SOC concept was presented for the first time in that paper and has been applied to many fields ever since such as earthquake,weather and population etc. It has been adopted thousands upon thousands times. SOC is a new method to observe and explain the complexity and mechanism of nature. The negative power is the direct proof of SOC,fractal and disaster are two exterior representations of SOC. A SOC system can be forecasted. China is an agricultural country to some degree. However,natural and social factors result in the frequent natural disaster,which has greatly affected the agriculture and economy of China. Thus,it is useful to study the characters of statistics and SOC of natural disasters of China. In this paper,the characters of statistics and SOC of exposure of natural disasters of China are discussed based on the concept of Self-organized criticality and fractal. Furthermore,the relationships between the scale and frequency of cities covered by flood,died people by drought and flood are constructed. For example,the relationship between the scale and frequency of cities covered by flood is logN=4.0957-0.577logr,that of died people by drought is logN=3.9486-0.5359logr,and that of died people of all disasters is logN=4.8645-0.6526logr. The paper also discriminates the relationship between the negative power and scales,it is found that the character of self-organized criticality of China disaster exposure exists objectivity,but the value of the negative power of relationship between the scale and frequency may change with different scales.