The police security should explore methods of underworld and vicious power cases inves-tigation,lead investigation by information,command cases by strategies,create outer conditions for fight against cases so as to realize the aim.

Besides the external causes such as family,society,historical progress,an important cause that the "underworld forces" have been growing stronger is that they have the common twisted humanity such as bullying the weak,greed,and peacockery.

On "the five enhancements" in the action of the striking blows at the underworld force for the public security bureau;

What the special struggle against Mafia_evil force in one northern city in Hunan has shown and a large number of cases exposed by media have reflected the process of the birth,growth and spread of crime of Mafia_evil force in China from the end of 1970 s to this early century.