Metasurface absorbers (MA) can absorb electromagnetic (EM) wave energy, reduce signal reflection or transmission, and are crucial for protecting sensitive electronic devices from EM interference. This article proposes a pseudo-waveform-selective metasurface absorber (PWSMA) based on a square-ring resonator structure with a lumped resistor, which can simulate the waveform-selection characteristics of nonlinear MA, achieving strong absorption of continuous wave or long pulse signals and low absorption of ultrashort pulses at the same operating frequency. The designed PWSMA basic unit exhibits a surface metal square-ring resonator structure with lumped resistance and comprises an intermediate dielectric isolation layer and a bottom grounding layer. The results show that the PWSMA has an absorption rate of 98.6% for continuous waves with a frequency of 3.3 GHz, while for ultrashort pulses with a pulse width of 0.5 ns at the same frequency, the absorption rate is only 43.9%, indicating significant selective absorption performance for continuous waves. The waveform-selection response characteristics based on linear MA mainly originate from the dispersion behavior of the resonator structure rather than the full wave rectification and frequency conversion characteristics of the nonlinear circuit. The absorption rate of PWSMA significantly increases as the pulse width increases. In particular, when the pulse width exceeds 100 ns, the absorption rate of the pulse wave reaches 98.3%, which is similar to that of continuous waves across the entire frequency range. In addition, the PWSMA cannot exceed the Rozanov limit in terms of the absorption range for pulsed and continuous waves. Results indicate that changing the resistance value can significantly adjust the absorption characteristics of the PWSMA for continuous waves and pulse signals.