Based on the Transverse Ising Model, the solution of the duration equation is derived using the Mean-Field approximation theory. The effects of exchange interactions on the surface of the system and the internal and external transverse field parameters on the ferroelectric-paraelectric phase transition were studied for single and double surface ferroelectric films with different total layers. The effects of various exchange interactions and transverse field parameters of ferroelectric thin films on the phase diagrams of single and double surface ferroelectric thin films were discussed. The results show the total number of thin films layers n, the number of surface layers, internal and external transverse fields, and surface exchange interactions will change the phase diagram of ferroelectric thin films. Using the size effect and surface effect of the film, increasing the total number of layers, surface layers and surface exchange interactions of the system can increase the phase transition temperature of the films and expand the ferroelectric phase area, which is conducive to improving the ambient temperature of the ferroelectric functional device.