Laser plasma flash is induced when a nanosecond Nd∶YAG pulsed laser with wavelength of 1064 nm is focused on monolayer aluminum film. The ignition time of laser-induced film plasma (tm) is calculated with simulation method, and the relationship between tm and the laser wavelength, incident laser energy, focusing spot radius and pulse width is obtained, respectively. The results show that tm increases with laser focusing spot radius and pulse width increasing, and decreases with laser wavelength and incident laser energy increasing. In addition, the smaller the ionization energy of thin film materials, the smaller tm. When impurities and defects exist in films, tm becomes small. Such results provide a certain reference to the research on the generation mechanism of laser-sustained combustion and detonation wave.