Safety-critical systems have evolved to use heterogeneous components to implement complex requirements, each component may adopt different computation models or modeling languages. Therefore, it is necessary to use complex modeling approaches to design those systems. AADL, as a multi-paradigm modeling language for safety-critical system architecture, is a good choice to design safety-critical heterogeneous systems because of its rich expressibility and well scalability. This study proposes a bottom-up AADL-SDL co-modeling approach that integrates functionality modeled by SDL through the AADL architecture model and provides a multi-task code generation approach for multi-core platforms. Firstly, AADL property sets are extended to support the capability of modeling functionality. Secondly, a multi-task code generation approach is proposed to transform AADL-SDL models to Ada code. Finally, a prototype tool is implemented to support AADL-SDL co-modeling and multi-task Ada code generation. The effectiveness of the method proposed in this study is analyzed based on the guidance, navigation, and control system scenarios.