Abstract: Based on thermo-acoustic effect, the graphene film with a substrate thinner than thermal penetration depth is studied both in theory and simulation. Firstly, the expressions of sound pressure in near and far field of graphene film thermophones are derived by using the thermal power balance equation of the thermophone and the thermalelastic coupled linear equations in gas. By comparison, the theoretical calculation results are in good agreement with the experimental results, which verifies the availability of the theoretical model. Then, the sound pressures in near and far field of graphene films are calculated by simulation method, and the results are compared with the theoretical values to show their good consistency, which validates the availability of the simulation calculation method. The analysis results show that the sound wave in far field of the graphene film is spherical, and approximately planar in near field. At low frequencies, the sound pressure level (SPL) in far field increases with frequency; while at high frequencies, the SPL in near field is nearly independent of frequency. The study in this paper presents a calculation and analysis method for the graphene film thermophone with a substrate thinner than the thermal penetration depth, and provides guidance for the experimental research on graphene film thermophones.