The equilibrium solubility of cesium chloride + europium trichloride + hydrogen chloride (0.11) + water (298.15 K) quaternary system at T = 298.15 K was investigated and the corresponding phase diagram was constructed. The two new compounds Cs5EuCl8 (.) 14H(2)O and Cs2EuCl5 (.) 4H(2)O were formed and obtained from the complicated system, both were characterized by X-ray, thermal analysis method of TG-DTG, DSC, ultra-violet absorption spectrometry and fluorescence spectrum. The fluorescence excitation and emission spectra of Cs5EuCl8 (.) 14H(2)O and Cs2EuCl5 (.) 4H(2)O were measured. The results show that upconversion spectra exhibit at 590 nm and 610 nm exited at 790 nm, and the upconversion intensity increase with the EuCl3 ratio increasing in CsCl.