The man-machine allocation of function of nuclear power plant is the focus of study reflecting human-computer interaction, and is also one of the key technologies in the human factors engineering of nuclear power plant. Task assigned to people to complete functions mainly include master main control room task and local task, which is necessary to consider whether they can be successfully completed by people. And at the same time there is a lack of systematic method system, practice experience and public literature discussion for the analysis of local operation task of nuclear power plants. This paper describes an application method system of man-machine allocation of function and local task in nuclear power plant. And with the man-machine allocation of function and local task analysis for emergency feed water tank cross-connection as an example,proved that the man-machine function allocation and local local task analysis method is validity feasible.