In this paper, silkworm excrement are processed by carbonization and activation processing to innovatively prepare silkworm excrement based microporous carbons (SEMCs). The unique microporous SEMCs/SnO2 composite nanostructure then can be skillfully constructed. The characterizations of crystallinity, microstructure and morphology of SEMCs and SEMCs/SnO2 clearly show the polycrystalline nanostructure based on amorphous SEMCs and tetragonal rutile SnO2, which is composed of semiconductor microcrystals of small-sized SnO2. The sensing properties of SEMCs/SnO2 composite sensor are studied by using static sensor test system. The prepared SEMCs/SnO2 sensor can effectively detect glycol with excellent sensing performances, including the high response value of 132, excellent selectivity and long-term stability. The hybridization process and the resulting numerous heterojunction interfaces originated from the biomass template of silkworm excrement may benefits the glycol sensing performance.