Abstract: The IV (insensitivity value) of characters of agronomy and quality in between 32 American and 12 Chinese key rice breeds have been evaluated, and the quality characters in between the most insensitive 14 American and 5 Chinese rice breeds have been contrasted. The results showed that the American rice breeds are insensitive in the rate of chalk, brown rice and head rice, especially in chalk rate. Also we selected several breeds, which are the most insensitive against temperature such as C94-403, Lemont etc. The utilization of those varieties is discussed in hybrid rice breeding in Chongqing.