Abstract: On exploring the relation of infants’ Executive Function and Theory of Mind, the previous researches just view inhibitory control as one of their common components but seldom take the difficulty level of inhibitory control into consideration. The research divided the difficulty of inhibitory control into high, moderate and low these 3 levels, and explored the influences that inhibitory control with different difficulty levels had on the correlation of infants’ Executive Function and Theory of Mind, with 3 Day/Night tasks B1, B2 and B3 and 3 False Belief tasks A1, A2 and A3. In Experiment 1, 48 4-year olds were tested, and the result shows that the 3 difficulty levels divided into have significant difference and that inhibitory control indeed behaves high, moderate and low levels. In Experiment 2, with the tasks in Experiment 1 that have significant difference, 144 3-year, 4-year, 5-year and 6-year olds were tested, and the result shows that the difficulty level of inhibitory control plays an important and great role in the relation of infants’ Executive Function and Theory of Mind.

Key words: inhibitory control, difficulty level, Executive Function, Theory of Mind