The probable inference has been ignored all the time because its conclusion is not always true. However, since it is unnecessary for its premise to be absolutely credible and its inference pattern to be strictly effective, it has been used in great extent in criminal investigation. During the criminal investigative activities for crac king cases, the premise of inference is impossible to be absolutely reliable due to the complex and changeable objective conditions, what's more, there are various flexible patterns of inferences in criminal investigation, so that it’s difficult to enable them to completely suit to the principles of logical inference, therefore, the inference implemented in criminal investigative activities may be, and should be the probable inference under most circumstances