We need to consider many factors to apply the civil presumption in the cases, such as the rules ,explanation, and applation of legal presumption based on policy; actual function of factual presumption based on experience.

As an important part of evidence act, the system of the civil presumption plays an important role in cognizancing verity of the civil judgement and opening the free evaluation of evidence.

The empirical analysis of 44 criminal presumptions in our criminal law indicates that they relax the proving requirement to the prosecution and shift the risk of doubt to defendants,deviating from the proof standard of beyond a reasonable doubt and directly threatening the values and interests protected by the principle of presumption of innocence.

During the criminal procedure, criminal presumption is an important method in identifying the case, which to some extent mitigates the difficulty of Public Prosecutor s proof.

The research of criminal presumption from the overseas is relatively mature, compared to that from the domestic.

As a measure of judging the facts in issue,the presumption of fact is practiced more widely than presumption of law in judicial areas.

As a measure of judging the facts in issue, the presumption of fact is practiced more widely than presumption of law in judicial areas.

It is a process that the judges make reasoning and logic considering to find the facts, Presumption of law is a conception contrary to presumption of fact, It is limited because the lawmaker can only prescribe clearly the foreseeable, universal presumption.

Afterwards, the author analyses the characters, definition and connection between fact inference and presumption of law, points that reasoning is the essence of the fact inference.