A new kind of dye LB films, in which dye molecules formed H-aggregates units with a shift of absorption band in voilet direction, is reported. Invertable optical recording effect has been observed in the LB films in the three-dimentional degenerate four-wave mixing experiment. The accumulating recording time needed to build up a stable grating in the film is about 80 ns(coresponding with 10 pulses) with the recording intensity of pulse beams of 30 MW/cm2. The main mechanism of the optical recording effect in the film is the light-induced transformation between H-aggregate and monomer structures of dye molecules, based on the po;ulation grating model in simplified three-state system.