This study aimed at developing a scale, "Technological Pedagogical Content Knowledge-Thinking Tools" (TPACK-TT), and exploring Chinese in-service primary teachers' TPACK concerning the use of thinking tools. By revising a previous Chinese TPACK survey and validating with exploratory factor analysis, a six-component (i.e., TK-TT, PK, CK, TPK-TT, PCK, and TPCK-TT) scale with 31 items was developed. Research data gathered from 204 primary teachers from a variety of schools revealed that teachers with different educational backgrounds and various overall teaching experiences did not show statistical differences in most components of the TPACK-TT. However, male teachers demonstrated significantly higher TK-TT and TPK-TT than female teachers, teachers with a bachelor's degree demonstrated significantly higher PK than those with only an associate degree, and teachers with longer experiences in teaching thinking had significantly higher TK-TT than those with fewer experiences. Stepwise regression further revealed that TPK-TT, TK-TT, and PK were significant predictors of in-service primary teachers' TPCK-TT. Implications for preparing teachers for teaching thinking were discussed.