The German Renewable Energy Sources Act (EEG) has been deemed successful in promoting German biogas production. However, the German state-level biogas production development (BPD) under the EEG has not been systematically studied and compared. This research aimed to study the German state-level BPD using the multivariate linear regression model with a dummy variable, and to spatially quantify the environmental and agricultural consequences using the geographic information system (GIS) technique to identify the necessities of regional-based analysis on Germany’s BPD. The empirical results indicated that Saxony-Anhalt was advanced in BPD, while farmers’ response from Bavaria to EEG was the weakest. The reason behind could be the differences in farmers’ personality traits and risk cognitions toward the biogas production investment. The spatial analysis indicated that Saxony-Anhalt had more severe environmental problems caused by the biogas production expansion than Bavaria. Therefore, to promote BPD in states such as Bavaria, an increase in the nationwide unified subsidy might lead to an overreaction of the EEG strong response states, e.g., Saxony-Anhalt, leading to more serious environmental problems. In the end, there is a need for more regional-based research on studying the BPD in Germany in the future to avoid the ambiguity of large-scale studies.