Freehand 3维超声是近年来超声图像3维重建技术领域的研究热点之一。在对3维超声按获取方式不同进行分类的基础上，阐述了Freehand 3维超声系统特点及其重建原理，对Freehand 3维超声重建算法进行了综述和比较分析，并指出了今后面临的主要挑战和未来发展方向。

The research of Freehand 3D ultrasound has been playing an increasingly important role in the 3D reconstruction techniques of ultrasound images in recent decades. 3D ultrasound is classified firstly according to different taking manners. Then the characteristic of Freehand 3D ultrasound system and the principle of 3D reconstruction for Freehand ultrasound images are illuminated. Finally, the overview and comparison analysis of Freehand 3D ultrasound reconstruction algorithms are provided. Synchronously some challenges and research orientations are also indicated.