Transaction abnormity monitoring method and device

The embodiment of the invention provides a transaction abnormity monitoring method and device. The transaction abnormity monitoring method comprises the steps: receiving a transaction request for a target user, wherein the transaction request comprises a corresponding to-be-transacted amount; obtaining pre-stored normal probability distribution data corresponding to the target user, wherein the normal probability distribution data is determined based on a transaction amount mean value of the target user in a first preset time period and a standard deviation corresponding to the target user; wherein the standard deviation is obtained by performing subdivision processing, local summarization processing and global summarization processing on the key values corresponding to the users in advance based on a preset rule, and each user comprises a target user; and according to the amount of money to be transacted and the normal probability distribution data corresponding to the target user, monitoring the abnormal co