In　the　system　of　Ce(NO3)(3)center　dot　6H(2)O　and　urea　solution　during　homogeneous　precipitation　method,　hydrothermal　homogeneous　precipitation　coupling　method　and　homogeneous　precipitation　method　with　additive,　X-ray　diffraction　(XRD)　and　transmission　electron　microscope　(TEM)　were　used　to　study　and　characterize　the　product　structures　and　morphologies.　The　outer　electron　configurations　and　the　energy　conservation　theory　were　used　to　analyze　the　reasons　for　stability　of　products　and　valence　state　change　of　cerium　ions.　The　results　showed　that　synthesis　technics　and　additives　had　a　great　effect　on　the　cerium　ion　compound　valence.　The　products　were　orthorhombic　Ce2O(CO3)(2)center　dot　H2O　with　Valence　(sic)　and　orthorhombic　CeO(CO3)(2)center　dot　H2O　with　valence　VI　by　using　homogeneous　precipitation　method　and　hydrothermal　homogeneous　precipitation　coupling　method,　respectively.　If　an　additive　(triethanolamine　or　triethylamine)　was　added　into　the　homogeneous　precipitation　system,　the　products　changed　into　a　mixture　of　orthorhombic　CeO(CO3)(2)center　dot　H2O　with　Valence　VI　and　cubic　CeO2　with　valence　IV.　It　showed　that　triethanolamine　or　triethylamine　had　strong　oxidizing　properties　and　played　a　catalyst　role　in　the　reaction.