In order to improve the photoelectric signal quality from position-sensitive anode of waveguide-gate thin film complex detector and reduce the influence of the multi-path broadening of the electron beams caused by the thin gate film, a direct extraction method of the complex detection signal of the waveguide gate based on micro channel plate was studied. According to the scattering physical model of electron beams with low energy in multimedia materials, the trajectory of incident low-energy electron beams was simulated by Monte Carlo statistical method in the gate film. Further more, accuracy deviation of signal extraction of the anode resulted from noises introduced from the waveguide gate was respectively analyzed under uniform distribution and Gaussian distribution. Accuracy deviation of signal extraction of the anode affected by the radial position shift of transmission electron beams in the process of transmission through the thin gate film was analyzed as well. The preamplification mode and series voltage controlled multi-stage cascade amplification mode were researched for weak photoelectric signal pulses came through the thin gate film to the anode. A fourth order Chebyshev low pass filtering method based on a circuit topology named Sallen-Key was proposed under additive Gauss distribution noise to reduce the influence of waveguide gate film on signal-to-noise ratio and make frequency response characteristics of signal wave form better. A peak sample and hold circuit of multi signal channels was presented as well. A complete and special platform was constructed to achieve the extraction of position sensitive signal from the waveguide-gate complex detection device, combined with parallel single point grounding connection mode of the whole readout system of anode signal and the direct extraction of position sensitive charge on wedge stripe anode. The signal extraction method of the device′s anode was verified in a vacuum chamber. The quasi-Gaussian impulse extraction signal with 2 μs pulse width and 200 kHz frequency was obtained.