形位公差是机械图样中的重要技术要求之一，由于其标注形式的多样性，因此在计算机绘图软件中难以采用统一的模型进行描述。本文运用了一种基于符号匹配的形位公差代号的标注方法，较好地解决了这一问题，并以此方法编写了一个形位公差代号的标注模块，在实际应用中取得了很好的效果。 Forming tolerance is one of the important technical requirements in mechanical drawing. Due to the diversity of its marked forms, it is difficult to describe by a unified model in computer graphics software. In this paper, we use a mark matching method based on symbol matching to form the position tolerance code, which solves this problem well. In this way, we write a label module of the shape tolerance code, which has achieved good results effect.