A method is proposed to calculate the photocurrent by measuring the output current and gain of microchannel plate, so as to measure the quantum yield. The quantum yield is measured in the near ultraviolet (200~380 nm) by the proposed method. The measurement results show that the quantum yield of microchannel plate is very low, and decreases rapidly with the increase of wavelength. The quantum yield of 200 nm wavelength is 10^-4 order of magnitude; the quantum yield of 320 nm wavelength is 10^-8 order of magnitude, and the quantum yield after 340 nm wavelength is very low and almost zero. The imaging device composed of microchannel plate and fluorescent screen can image the flame of alcohol lighter, but the image is sparse, while the image of traditional Cs₂ Te photocathode ultraviolet imaging device is dense, which is consistent with the situation of low quantum yield of microchannel plate and high quantum yield of Cs₂ Te photocathode. When a 350 nm high pass filter is placed at the front of the imaging device, the detected flame image of the alcohol lighter disappears. When imaging the illuminated target, it can be imaged if the light source is a 254 nm mercury lamp; but it cannot be imaged, if the light source is a 365 nm mercury lamp. The results show that the spectral response of microchannel plate is mainly below 350 nm wavelength, which is consistent with the measurement results of quantum yield. Finally, the resolution of the imaging device is measured as 32 lp/mm, which is the same as that of the traditional Cs₂ Te photocathode ultraviolet imaging device. Because the imaging device composed of microchannel plate and fluorescent screen does not use photocathode, it has the advantages of low price, long life and high reliability, so it can be used under the condition of strong ultraviolet signal or short imaging distance.