Altermagnets, collinear antiferromagnets with vanishing net magnetization yet momentum-dependent spin splitting, open a new route to topology and strong correlations. In this work, we propose a general framework to construct nearly topological flat-band (TFB) models in $d$-wave altermagnets via stacking bilayer Chern insulators with spin flip and intralayer rotation. This framework is concretely realized on altermagnetic checkerboard and Lieb lattices. By tuning hopping parameters, we obtain TFBs with a flatness ratio exceeding 10, whose topology is fully captured by the spin Chern number. These altermagnetic TFB models support a stable fractional quantum spin Hall state, thereby realizing the coexistence of altermagnetic symmetry and topological order. Our work not only provides a unified scheme for constructing altermagnetic TFB models but also establishes a platform for exploring fractionalization in altermagnetic materials.

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• Flat bands
• Fractional quantum Hall effect
• Topological insulators
• Altermagnets
• Strongly correlated systems
• Exact diagonalization
• Tight-binding model