3D 打印计算机辅助设计( CAD) 模型转换标准三角形语言( STL) 文件过程中，存 在表面精度下降，结构体信息丢失的问题． 文中提出一种基于 CAD 模型外轮廓线的自适 应分层方法． 即采用角度分组思路，通过引用一系列过 Z 轴的平面对 CAD 模型等转角剖 切，并将剖切面与模型外表面相交轮廓线绕 Z 轴旋转至 XOZ 平面内进行轮廓线微分段处 理，然后利用三角函数关系、概率统计方法、加权方法综合计算获得3D 打印 STL 文件每 一层的自适应分层厚度值． 打印实例分析结果表明，文中算法可减少 STL 文件的转换误 差，提高3D 打印精度和打印效率． 

 In the process of converting CAD ( Computer Aided Design) models into STL ( Standard Triangular Language) models in three-dimension ( 3D) printing，there exist such problems as reduction of surface accuracy and loss of structure information． In this paper，a adaptive layered method is proposed based on the contour line of CAD models，with an approach of angle grouping，by referring to a series of planes containing Z axis to cut CAD models with equal turning angle， rotating the intersecting contour lines of cutting planes and model surfaces to XOZ plane around the Z axis，and dividing the contour lines into differential segments，applying trigonometric function relations，probability and statistic method，and weighting to calculate the adaptive layered thickness of each layer for 3D printing STL files． The results of model printing show that the algorithm can reduce conversion error of STL files， improve printing accuracy and printing efficiency of 3D printings．