本文讨论了孕周的超声无损估计方法。传统上，对孕周的估计是通过Ｂ型超声测量胎儿器官的有关参数，辅以经验公式而得到。但是由于经验公式无统一形式，且参数皆单独使用，估计结果离散度大，难以实用化。本文对Ｂ型超声测量所得胎儿参数应用数量化理论，建立孕周自动估计的方法。由于在实际应用中，应用数量化理论所得的相应正规方程，难以满足通常求解方法的前提条件，本文引入广义逆矩阵理论求解正规方程．另外，本文进一步讨论了应用数量化理论中的项目选取和类目划分问题，并分析比较了不同的项目、类图划分方法。通过上述工作建立的孕周超声无损估计方法，运算时间短，精度高，有一定的实用性。　 This article discusses the ultrasound nondestructive estimation of gestational age. Traditionally, the gestational age is estimated by measuring the parameters of fetal organs by B-mode ultrasound, supplemented by empirical formulas. However, due to the fact that the empirical formula has no uniform form and the parameters are all used separately, the estimation result has a large dispersion and is difficult to be put into practical use. This article applies quantitative theory to the fetus parameters measured by B-mode ultrasound, and establishes a method of automatic estimation of gestational age. Due to the fact that it is difficult to meet the prerequisites of the usual solution using the corresponding normal equations obtained from the quantitative theory in practice, the generalized inverse matrix theory is introduced to solve the normal equations. In addition, this article further discusses the application of quantitative theory of project selection and category classification issues, and analysis of different projects, class diagram division method. Through the above work to establish gestational weeks ultrasound nondestructive estimation method, the computing time is short, high precision, has some practicality.