Biogas, as the product of anaerobic fermentation, is one of the main routes to utilize bioenergy. The biogas production rate is determined by lots of factors, of which temperature determines most. However, when operating in the cold climate or cold areas, the low digesting temperature often results in a relatively low efficiency or even a suspension in the fermentation process. This paper proposes a self-excited heating method to increase the digesting temperature in cold weather. It utilizes the self-produced biogas as fuel to generate heat for heating the biogas digester. The influence of this method on biogas production rate and digesting temperature are verified in this study. The results show that the digesting temperature increases about 3%–9% with a self-excited heating method for both household-scaled biogas digester and industry-scaled digester.