The utility model discloses a semitrailer with protect function, the semitrailer includes locomotive, trailer board, controller, suggestion type reflector, prevents being drawn into the device and prevent pressing protection device, and the locomotive includes the locomotive wheel, has in the forward -mounted of locomotive wheel and prevents pressing protection device, and locomotive and trailer board rotate to be connected, and the trailer board includes trailer wooden handcart wheel, takes turns the place ahead at the trailer wooden handcart and is equipped with and prevents pressing protection device, and the suggestion type reflector that has been used for the warning effect is installed to the automobile body front end. The utility model discloses a multiple protection device can prevent effectively that the trailer from pressing personnel, support personnel's safety of life and property. The utility model discloses can prevent effectively that the trailer is drawn into the vehicle bottom at the in -process that turns round with personnel, avoid personnel and loss of property, the unsafe factor of the in -process of just driving a vehicle falls to minimumly.