Integrating artificial intelligence (AI) into computer-aided design (CAD) has shown the potential to transform design and manufacturing processes, enabling more efficient, intuitive, and intelligent workflows. In recent years, the application of AI to 3D CAD model generation tasks has gradually emerged. To better enable researchers to understand the current research status of the AI-based CAD generation field and to inspire them to conduct further research, this survey explores the role of AI in 3D CAD model generation tasks that utilize various representations and conditions, ranging from traditional machine learning to LLM-based approaches. Additionally, AI applications in other extended CAD areas are also touched upon in the survey. Finally, we analyze current progress, identify challenges and limitations faced by this field, and propose possible directions for future work.