In this paper, we investigate the correlation between broad-line and radio variations for the broad-line radio galaxy 3C 120. By the z-transformed discrete correlation function method and the model-independent flux randomization/random subset selection (FR/RSS) Monte Carlo method, we find that broad H beta line variations lead the 15 GHz variations. The FR/RSS method shows that the H beta line variations lead the radio variations by a factor of tau(ob) = 0.34 +/- 0.01 yr. This time lag can be used to locate the position of the emitting region of radio outbursts in the jet, on the order of similar to 5 lt-yr from the central engine. This distance is much larger than the size of the broad-line region. The large separation of the radio outburst emitting region from the broad-line region will observably influence the gamma-ray emission in 3C 120.