The traditional biogas reactor made of glass fiber-reinforced plastic decreases the performance of biogas fermentation under low temperature condition because it can’t remain the inner temperature. Therefore, to learn the characteristics of reactor wall will help to give guidance to the design of novel biodigester with thermal insulation and thus increase the biogas productivity by utilizing the metabolic heat. In this work, the mechanical and thermal performances of biodigester wall made of organic glass fiber-reinforced plastic were investigated. The results indicated that this traditional biodigester possessed high mechanical intensity and low thermal insulation. And it was anti-acids rather than anti-alkali. Furthermore, the experiments reveal that the compositions and structure of this traditional biodigester should be further modified to enhance the thermal insulation to remain the energy for biogas fermentation by methanogen.