The invention relates to a method for preparing a tin dioxide semiconductor film by a laser technology and an experimental technology for annihilating microstructure defects thereof, belonging to the technical field of semiconductor film preparation technology. Tin dioxide is an n-type semiconductor functional material arousing extensive attention in recent years, and has a broad application prospect in the fields of microelectronics industry, photoelectronic device, solar battery and the like. A film is deposited on a glass substrate at room temperature by a pulsed laser deposition method while controlling certain technological parameters to obtain the tin dioxide semiconductor film. The film has multiple microstructure defects and thus is limited in application. However, the film with microstructure defects is subjected to in-situ annealing at 300 DEG C for 2 hours by use of a high-resolution electron microscope, so that the technology for annihilating the microstructure defects of the tin dioxide semiconductor film is simply and successfully implemented, and a no-defect technology of a film microstructure is realized. The method has potential application value in the field of film preparation.