In this paper,a multiwavelength laser is realized based on an electro optic phase modulator (PM) and a Fabry Perot (F P) cavity in fiber ring.0.2 nm and 0.4 nm wavelength space spectra were observed respectively in the experiment.With this method,one can obtain a laser souce which simultaneously emits multiwavelength and fits for the standard of ITU T on wavelength diviesion multiplexing (WDM).