The phase transition of CdSe nanocrystallines from zinc blende to wurtzite phase can be controlled by varying the volume ratio of ethanolamine (EA) and water (WA) in their mixed solution and the morphologies of the CdSe nanocrystals are controlled simultaneously. The phase transition has been demonstrated by XRD patterns and HRTEM images. The samples are investigated by Raman spectrum. The Raman shifts of the samples show a gradual blue shift with the gradual transformation from zinc blende to wurtzite CdSe phase. This method is convenient and controllable which can provide a strategy way to control the phase and morphology of the nanomaterials and study their phase transitions in nanoscale field.