This thesis mainly deals with the synthesis and characterization of polysilazanes and hyperbranched polycarbosilazanes with desired functional groups.Firstly, three polysilazanes were synthesized via ammonolysis of mixture of MeHSiCl_2 and MeViSiCl_2 with different feeding ratios. Then, the forth polysilazane was prepared by further polymerization of the third polysilazane with NH_4Cl as the catalyst. The UV-curing and pyrolysis behaviors for the polysilazanes are also studied. Spectral analyses of the poly...