Technical terms in Tian Gong Kai Wu are essential carriers of ancient Chinese sci-tech culture. With the combination of the evaluative model based on translator behavior and the perspective of “thick translation”, this paper describes and compares the translators’ behavioral dispositions of the English version by E-tu Zen Sun and Shiou-chuan Sun on the notes of technical terms. It is concluded that the behavioral dispositions of Sun’s on the notes concerned are categorized into three types, containing intra-pragmatism, intra-extra-pragmatism and extra-pragmatism based on intra-truth-seeking due to the confinement of internal and external translation factors. It is noted that intra-translation behavior occurs in both internal and external texts, in which notes in external texts are information-oriented, containing explanatory notes, referential notes, comparative notes, explanatory misinterpretations or the mixture; while extra-translation behavior occurs mostly in external texts, in which the notes are research-oriented, containing exploitative notes, evaluative notes and controversial notes. Based on this research, extensions could be made in both the subjects of studies on English versions of Tian Gong Kai Wu and the theoretical framework.