A method for transmitting data in an Internet of Vehicles and a terminal device disclosed in the present disclosure allow the determination of a resource used for multiple transmissions of a sidelink and favor an increase in the reliability of data transmissions. The method includes a first terminal receiving first control information transmitted by a second terminal. The first control information is used for determining resource information used for multiple transmissions of a sidelink. The method also includes the first terminal determining, on the basis of the first control information, a resource used for multiple transmissions of the sidelink.