The adjustable generation of dissipative soliton resonance pulse and randomly chirped pulse in a square-wave fiber laser is proposed and demonstrated. A chirp measurement system is employed to investigate the output chirp characteristics. The results show that the adjustable generation of dissipative soliton resonance pulse and randomly chirped pulse can be achieved by adjusting the polarization controller inside cavity. The spectrum of dissipative soliton resonance pulse has a pedestal with two steep edges and a narrow spike, and the corresponding pulse chirp is linear and low at the central part while nonlinear and large at the edges. The chirp of randomly chirped pulse is irregular, and the spectral shape and width hardly change with the pump power.