A ranging system, characterized in that the ranging system comprises a ranging apparatus and a terminal device wherein the ranging apparatus comprises: a measuring wheel, a rotating shaft disposed on the measuring wheel, and an electronic counter connected to the rotating shaft and used to obtain distance information, in real time, of the route which the measuring wheel has already traveled; wherein the ranging apparatus or the terminal device further comprises an angle sensor configured to obtain angle information, in real time, when the measuring wheel is traveling; communication modules are arranged on the terminal device and the ranging apparatus, respectively, to transmit data between the ranging apparatus and the terminal device; the terminal device includes data processing module configured to generate a traveling trajectory diagram of the measuring wheel, in real time, based on the distance information from the electronic counter and the angle information from the angle sensor; the terminal device further comprises a storage configured to store a predesigned traveling trajectory diagram; characterized in that, the data processing module is further configured to monitor, on the basis of the predesigned traveling trajectory diagram, the generated current traveling trajectory of the measuring wheel determined based on the distance information and the angle information, and to output deviation data when the generated current traveling trajectory of the measuring wheel deviates from the predesigned traveling trajectory diagram, wherein the terminal device further comprises a prompt module configured to perform direction and/or distance prompt based on the deviation data to indicate the user to correct the current traveling route of the measuring wheel, wherein the terminal device further comprises a camera configured to obtain, in real time, a scene image in the traveling direction of the measuring wheel, and the prompt module is configured to provide the direction and/or distance prompt on the scene image. a measuring wheel, a rotating shaft disposed on the measuring wheel, and an electronic counter connected to the rotating shaft and used to obtain distance information, in real time, of the route which the measuring wheel has already traveled; wherein the ranging apparatus or the terminal device further comprises an angle sensor configured to obtain angle information, in real time, when the measuring wheel is traveling; communication modules are arranged on the terminal device and the ranging apparatus, respectively, to transmit data between the ranging apparatus and the terminal device; the terminal device includes data processing module configured to generate a traveling trajectory diagram of the measuring wheel, in real time, based on the distance information from the electronic counter and the angle information from the angle sensor; the terminal device further comprises a storage configured to store a predesigned traveling trajectory diagram; characterized in that, the data processing module is further configured to monitor, on the basis of the predesigned traveling trajectory diagram, the generated current traveling trajectory of the measuring wheel determined based on the distance information and the angle information, and to output deviation data when the generated current traveling trajectory of the measuring wheel deviates from the predesigned traveling trajectory diagram, wherein the terminal device further comprises a prompt module configured to perform direction and/or distance prompt based on the deviation data to indicate the user to correct the current traveling route of the measuring wheel, wherein the terminal device further comprises a camera configured to obtain, in real time, a scene image in the traveling direction of the measuring wheel, and the prompt module is configured to provide the direction and/or distance prompt on the scene image.