A silazane oligomer with low viscousity and latent active groups（Si-H and Si（CH = CH₂)) was prepared by coammonolysis of MeSiHCl₂ and Me（CH₂=CH) SiCl₂. H₂PtCl₆（dehydrated) and dicumyl peroxide (DCP) were found to be effective to catalyse or initialise crosslinking of the silazane oligomer respectively. The crosslinked polymer was pyrolysed in a tube furnace to obtain high yield(over 74%wt)ceramic at 1273K.