Co3O4 is often used to detect H2O2. However, there are many problems such as low sensitivity and the long detection time when detecting H2O2 in various cobalt oxide composites. Therefore, it is a great challenge to develop different morphologies of the Co3O4 electrode to improve the detection performances of H2O2 effectively. In this paper, we had successfully prepared a novel Co3O4/reduced graphene oxide/carbon cloth (Co3O4/rGO/CC) composite. We used a simple template method. Co3O4 nanosheets with a diameter of about 47.7 nm were obtained by using graphene oxide as a template. Then, CC was used as a three-dimensional conductive support material. CC can inhibit the agglomeration of rGO to increase specific surface area and to enhance the conductivity of Co3O4. In this study, the electrochemical performances of the Co3O4/rGO/CC electrode were tested by the electrochemical workstation. The trigger response of the modified electrode was reduced by 0.067% and the relative standard deviation was 0.013% after 30 consecutive tests. The range of linearity was 0.387–63.523 mM. Besides, this electrode has the limit of detection (0.022 μM) and a higher sensitivity (0.9683 mA mM−1 cm−2). It indicated that the electrode has excellent electrochemical sensing performance and high stability. These excellent performances are mainly due to the synergistic effect of Co3O4 nanosheets, rGO, and CC. [ABSTRACT FROM AUTHOR]