In this paper, a novel compensation technique is presented for mitigating dispersion in fiber optic microwave frequency transfer systems. By introducing an additional carrier light into the transmission link, the system effectively eliminates the effect of dispersion on temperature in the fiber link. The experimental results show that the long-term stability of microwave frequency transfer over a 100 km optical fiber link is better than 10^-18/d. This remarkable result strongly demonstrates the feasibility of our proposed scheme, while also highlighting its significant practical significance in ensuring the long-term stability of microwave frequency transfer across hundreds of kilometers of optical fibers.