Electron-optical devices with microchannel amplification have many advantages, except poor noise characteristics. In order to increase gain and reduce a noise factor a layer with increased secondary emission is deposited on the top of a contact conducting layer at the entrance of channels. Effects, arising in the channel amplifier with the high-efficiency emitter, are investigated in this work using the computational method, developed by the author. A computational method for simulation of stochastic processes of an electron multiplication is based on 3D Monte Carlo simulations and the theorems of serial and parallel amplification stages proposed by the author. The method provides a high calculation accuracy with minimal cost of computations. The computational model is used to investigate the effect on the noise factor of the incidence angle of the input electron beam, nonuniformity of the emitter surface, the depth and secondary emission yield of the high-efficiency emitter.Keywords Microchannel electron amplifier · Monte Carlo simulations · Nonuniformity of an emitter surface · High-efficiency emitter · Noise factor