To improve the dynamic range of microwave photonic vector network analyzers (MPVNA) during pulse measurements, a software gate control scheme is proposed. This scheme utilizes the temporarily idle receiving channel to receive a pulse square wave that is sourced from the control signal generated by the pulsed excitation, thus generating a gate control signal. By using this gate control signal to control the pulse response of the device under test that has been collected, the signal-to-noise ratio and the measurement's dynamic range are effectively improved. The pulse scattering parameters (S-parameters) of a 10 GHz band-pass filter were measured. Experimental results show that under a 1% duty cycle pulsed excitation, the measurement dynamic range with the software gate control applied has increased by approximately 20 dB compared to when no gate control control was used. The S₁₁ and S₂₂ parameter curves measured after gate control processing are also smoother and more stable due to the improvement in the signal-to-noise ratio.