The output characteristics of a chaotic fiber laser with optical injection were studied experimentally. After a chaotic fiber laser with a ring cavity was built, the nonlinear Kerr effect of the fibers was employed for generation of chaotic laser. The chaotic laser generated by the master laser was injected into a chaotic erbium-doped fiber laser via an optical isolator and a fiber coupler to achieve external optical injection. The time series, spectra, autocorrelations, stabilities, and complexities of the chaotic signals generated by the slave laser were studied after chaotic signals of different power were injected from the master laser to the slave laser. The results show that the time series of chaotic signals after optical injection are random and the amplitude frequency distributions fit Gaussian distribution. The spectra have no obvious periodic characteristics, and the autocorrelations are excellent. The chaotic output of an erbium-doped fiber laser with optical injection ensures a complex and more stable chaotic source.