A kind of all-optical control method based on the deposition of graphene oxide dispersion in long period fiber grating is proposed and experimentally validated. Pumped by an external vertical light, graphene oxide generates heat and changes the phase difference of the cladding mode of long-period fiber grating. Due to the effect of thermal expansion, the grating period of the part covered by graphene oxide is changed, which makes the resonance spectrum shift. The maximum modulation depth can reach 10.6 dB, and the maximum resonance spectrum can be red-shifted by 12.8 nm. It is found that the number of times to deposit graphene oxide dispersion with the same concentration influences the experimental results. By depositing graphene oxide dispersion at the same position of the same grating once and three times respectively, it is found that the more uniform graphene oxide film can be obtained on the surface of optical fiber by three times of deposition, which enhances the interaction between light and graphene oxide, and has higher modulation efficiency and tuning efficiency. Finally, the time response test is carried out, and the response speed of the long period fiber grating after three times of deposition can reach 0.61 ms. It is found that the graphene oxide dispersion can be deposited more evenly on the surface of the optical fiber, thus obtaining greater thermal conductivity.