The invention discloses an oral cavity scanning system based on a TOF (Time of Flight) technique. The oral cavity scanning system comprises a detection device and a mobile terminal, wherein the detection device is positioned on a tooth brush and comprises a TOF sensor module, a main control circuit board and a wireless communication module; the TOF sensor module is positioned on a brush head, is arranged opposite to brush hair and is used for transmitting and receiving light signals, used for acquiring depth information inside an oral cavity and used for transmitting the depth information to the main control circuit board; the main control circuit board is used for processing the received oral cavity depth information to obtain 3D (Three Dimensional) image information of the oral cavity, and used for transmitting the 3D image information of the oral cavity to the mobile terminal through the wireless communication module. By adopting a non-contact mode, the oral cavity scanning system is low in cost, small in size, convenient to use and capable of scientifically and accurately detecting situations inside oral cavities.