In this paper, we report a simple technique for making bulk Si-based ceramics from polymeric precursor. In this technique, a porous polymer preform with high porosity is used as a template. The preform is thermally decomposed before the precursor during pyrolysis to form interconnected pores for releasing gaseous species resulting from pyrolysis of precursors to avoid the formation of cracks within resultant ceramics. The thermal decomposition behavior of both template and precursor is studied for determining the proper pyrolysis procedure. The microstructure, porosity, and mechanical strength of the ceramics obtained are characterized.