There are some delay elements in photoelectronic imaging processes, such as phosphor screen, photoconductive target, etc., and these lead to the time delay. The former originates from the transience capture of carriers which is produced before recombination luminescence in the luminous crystal excited process, and the time dispersion of the electrons release in trap level determines the delay of the luminous delay process. Whereas, the latter originates from the lifetime dispersion of semiconductor minority carriers and the capacitive delay of scanning electron beam charging the target. It can be fairly well verified by theoretic analysis and experiment that photoelectronic imaging delay can be approximately divided into: proportionality functional delay type, exponential functional delay type, and hyperbolic functional delay type. The three kinds of delays have different temporal modulation transfer functions. In this paper, we give the concrete analysis of them.