The utility model relates to an all-normal-dispersion dissipative-type nanosecond-level passive mode-locking optical fiber laser capable of reforming. The all-normal-dispersion dissipative-type nanosecond-level passive mode-locking optical fiber laser capable of reforming includes an all-normal-dispersion dissipative-type picosecond pulse generating subsystem, a pulse widening subsystem and a three-level amplifying subsystem having a filtering function. The all-normal-dispersion dissipative-type picosecond pulse generating subsystem is connected to the three-level amplifying subsystem having the filtering function through the pulse widening subsystem. The all-normal-dispersion dissipative-type nanosecond-level passive mode-locking optical fiber laser capable of reforming provided in the utility model has characteristics of high pulse energy, good heat dissipating effect, easy modulation, and simple and convenient operation. And the all-normal-dispersion dissipative-type nanosecond-level passive mode-locking optical fiber laser capable of reforming can function as a front end system for chirped pulse amplification.