The evolution characteristics of Q-switched mode-locked rectangular noise-like pulses were studied in an L-band erbium-doped fiber laser. By varying the pump power and polarization state, continuous-wave and Q-switched mode-locked based on rectangular noise-like pulses with 1600 nm central wavelength were realized in the fiber laser. The fundamental repetition rate and the maximum pulse width of the rectangular noise-like pulse were 1.64 MHz and 17.51 ns, respectively, and the repetition rate of the Q-switched mode-locked rectangular noise-like pulse could be tuned in the range of 8.14-18.18 kHz. The evolution trend of the Q-switched envelope width was opposite to that of the rectangular pulse width. The maximum average energy of the Q-switched envelope and the rectangular pulse inside the Q-switched envelope reached 1115.5 nJ and 24.89 nJ, respectively. The average peak power of the rectangular pulse was maintained at approximately 1 W. These results may aid in understanding the dynamic characteristics of Q-switched mode-locked rectangular noise-like pulses in L-band fiber lasers.