Based on the collisional radiative model from the flexible atomic code, X-ray emission spectra for L-shell of Li-like oxygen plasma consisting of three kinds of oxygen ions (Li-like oxygen ion and another two neighboring ions) are simulated. Atomic processes in the model include dielectronic recombination(DR), radiative recombination(RR), collisional ionization(CI) and resonance excitation(RE) from the neighbouring ion charge states of the target ion (Li-like oxygen ion). It is found that DR, RR, CI and RE, other than direct collisional excitation, are very important processes by analyzing the contribution of different atomic processes to the X-ray spectum. In addition, the relationship between X-ray wavelengths, relatively radiative intensity and the electronic temperature can be seen fro