The present invention discloses a method and apparatus for monitoring degree of attack on a system. The method comprises: collecting data information of at least one data-corruption attack effect evaluation indicator, wherein data-corruption attack effect evaluation indicators are the number of pieces of falsified user account information, the number of deleted user account information, the number of added user account information, the number of falsified registry keys, the number of deleted registry keys, the number of added registry keys, the number of falsified files, the number of deleted files, the number of added files, the number of terminated processes, and the number of created processes; determining an attack effect value of each data-corruption attack effect evaluation indicator according to the date information of each data-corruption attack effect evaluation indicator; and determining degree of attack on a target system according to the attack effect value of each data-corruption attack effect evaluation indicator and a weight of each data-corruption attack effect evaluation indicator. Therefore, degree of attack on a system can be accurately monitored.