Carboxy carbon nanotubes and dialyzed graphene oxide were bound via amio and carboxyl groups using polydopamine as a cross-linking agent to form a three-dimensional mixed aerogel (MA) with a hierarchical porous structure. Silver nanoparticles were loaded in situ onto MA to develop an efficient electrochemical method for the detection of hydrogen peroxide in foods. The response current to hydrogen peroxide of AgNPs-MA modified electrode was 24.5 times higher than that of bare glassy carbon electrode under the optimal conditions (pH 7.4, working bias of -0.4 V and 5 μL of modified electrode solution). Chronoamperometry was used to detect hydrogen peroxide rapidly and sensitively. The peak current of the modified electrode had a good linear relationship with the concentration of hydrogen peroxide, which was fitted the following equation: I = 0.32c + 1.66 (R² = 0.9993), and the limit of detection (LOD) was 0.02 μmol/L (signal-to-noise ratio, R_SN = 3). In addition, the electrochemical sensor had high accuracy, stability and anti-interference performance, and could be reused. The sensor was applied to the monitoring of hydrogen peroxide in milk, with a recovery rate of 98.1%–98.8% and a relative standard deviation (RSD) of 0.58%–2.28%. It is expected to be applied to the rapid trace detection of hydrogen peroxide in foods.