The present disclosure relates to a picture projecting method and apparatus and a terminal device. The method comprises: receiving a command of projecting a first picture onto a display terminal; compressing the first picture to obtain a compressed first picture, and projecting the compressed first picture onto the display terminal for display; and compressing a second picture to obtain a compressed second picture, and transmitting the compressed second picture to the display terminal for carrying out caching, wherein the second picture is a picture other than the first picture in the terminal device. According to the picture projecting method and apparatus and the terminal device which are disclosed by the present disclosure, the picture projection efficiency can be improved.