In a CVT system, torque transmission relies on the friction between a steel belt and variable-diameter pulleys. The active sulfur and phosphorus in CVTF’s antiwear additives can alter friction characteristics through tribochemical reactions. This study uses the Falex ring-on-block tester to explore the impact of butylated triphenyl phosphorothionate anti-wear agent (AW1) on the CVT friction transmission. The SEM, EDX, and XPS analysis of the tribosurface shows that during friction, AW1 reacts with Ca detergent to form calcium phosphate tribofilms. Greater the tribofilm coverage leads to better torque transmission. The amount of AW1 significantly influences the tribofilm distribution. QCM-D adsorption experiments indicate that when AW1 reaches 0.5%, its adsorption type changes abruptly, hindering the calcium phosphate tribofilm formation and exacerbating corrosion, thus reducing wear resistance. This study determines the optimal AW1 concentration to balance effective tribofilm formation and prevent excessive corrosion in CVTF.