In rubidium atomic magnetometers, the traditional heating structure for large-scale atomic vapor cells suffers from limited heating surfaces and asymmetric heat dissipation paths, leading to uneven temperature distribution and degraded measurement performance. To address this issue, an optimized external heating structure for cubic rubidium vapor cells is proposed. The design features multi-surface heating and a silica aerogel-filled interlayer to reconstruct heat conduction paths and thermal resistance distribution, thereby improving temperature uniformity and overall magnetometer detection performance. Finite element steady-state heat conduction simulation is employed to optimize key parameters such as heating surface layout, insulation thickness and thermal conductivity, revealing the synergistic mechanism of multi-surface heating and insulation interlayer for temperature field homogenization. An optically pumped rubidium atomic magnetometer platform is established to conduct comparative experiments on temperature distribution and frequency response. Experimental results demonstrate that the improved structure reduces the temperature variation coefficient from 0.003 9 to 0.002 2, representing an approximately 43.59% improvement in temperature uniformity, and enhances the average frequency response amplitude by 16.15% over the 1~100 Hz test band. Under non-magnetic heating constraints, this structure achieves effective overall temperature homogenization, providing a feasible temperature control scheme for high-sensitivity rubidium atomic magnetometers and their engineering applications.