Implementing STEM (science, technology, engineering, and mathematics) education in early childhood education has received increasing attention in recent years. STEM process skills developed during the early years have lifelong positive effects on young children. In this study, we developed the Children's STEM Habits of Mind Questionnaire (CSHMQ) and validated it in a sample of 231 Chinese preschoolers (M[subscript age] = 4.77 years, SD = 1.19). Items in the questionnaire were generated from literature and selected based on the factor analysis to ensure the scope, content, and construct validity of the scale. Results revealed Science Process Skills, Encoding and Decoding Skills, and Engineering and Numeracy Skills as the three dimensions of the questionnaire with high internal reliability. The total score of the questionnaire and the three sub-factor scores were all positively correlated with children's age, which demonstrates its preliminary validity. The CSHMQ provides a professional tool for early childhood researchers and practitioners to assess children's STEM process skills, thereby providing evidence for planning and adapting STEM instructional practices to better promote children's development.