The near-field target of fuze has commonly extended characters. The fluctuation characters of extended target should be considered deliberately when designing a fuze. In this paper, the theory of fluctuation and the methods to cope with the fluctuation are discussed primarily. At first, several reasons of the fluctuation are introduced. Analysis shows that the extended target has inevitably the fluctuation characters. Next, the design methods to cope with the fluctuation are discussed; simulation and experiment are conducted. The result proves the validity of design methods to cope with the fluctuation.