Abstract: As a measure of judging the facts in issue, the presumption of fact is practiced more widely than presumption of law in judicial areas. The structure of syllogism decides that the proving standard of basic fact must reach or exceed the "high probability". Only by this way can we guarantee the accuracy of the presumptive fact One of the preconditions of presumption is to find precisely the point of junction between the basic fact, the presumptive fact and the rule of thumb. In judicial practices, the presumption of fact faces the contradiction between the strictness of syllogism and the dissimilarity of results. The way to solve this problem, in my view, can be proposed by regulating the qualification of presumption of fact in law, by opening the train of thoughts of judges to the public, by unifying the scale of judgments in all courts.