This study explored the developmental tendency of young children’s (4～6 year old) metamemory monitoring (EOL/JOL/JOC), including the age differences on the level, the developing speed and the metamemory efficiency. There were 91 children randomly selected to participate. Items were 20 pairs of pictures, in which half were antonymous picture pairs, and the remaining half were unrelated pictures pairs. Two of 10 pairs were used to practice. The remaining 8 pairs were randomly displayed by computer for 3 s each, with an interval of 2 s. Before studying, participants were asked to make an aggregate EOL by responding to a question. Following the EOL, participants studied 8 pairs only once and made their JOL for 8 pairs by responding to a question followed by a cued-recall test. The experimenter instructed them to make an aggregate judgment of confidence. A MANOVA, Age(3)×Item difficulty (2:easy vs. hard), was carried out. The results yielded overall main effect was significant, Wilks’λ= .91, p <.05, for age, Wilks’λ= .72, p <.05, for item difficulty and Wilks’λ= .93, p =.58, for the interaction. The interaction of age and item difficulty was significant on JOC and we conducted a simple effect, the main effect of age was significant when task was difficult, M= 1.44, SD =1.46, for 4-year-old, M= .65, SD =.71, for 5-year-old, and M= .46, SD =.61, for 6-year-old. Secondly, the slope of development curve was computed to examine the differences in developmental rate (EOL/JOL/JOC). When the task was difficult the magnitude of slope as follows: k JOC = .79, k EOL = .06, k JOL =.40, for the age of 4-5, and k EOL =.71, k JOL =.54, k JOC =.19, for the age of 5-6. Finally, a Paired t–test was used to compare the differences between predicted recall and actual recall. Under the easy task condition, the difference were significant, tEOL(30)=-5.38,p<.001; tJOL(30)=-4.01,p<.001;tJOC(30)=-3.08,p<.01,for 4-year- old, tEOL(29)=-6.51,p<.001, only for EOL of 5-year-old, and the difference was not significant for 6-year-old . All of children overestimated their recall performance when the task was difficult. The conclusions as follows: children’s monitoring accuracy increases from 4 to 6 years old. Accuracy is better on an easy task than a difficult task. The developing speed of 3 monitoring judgments is different, under the difficult task condition, JOC is the first one at the age of 4～5, EOL and JOL develop quickly at the age of 5～6. All of children exhibit to overestimate their recall performance when the task was difficult. Whereas, under the easy task condition, 4-year-old children underestimate their actual recall; 5-year-old children exhibit accurate monitoring on JOL and JOC, but they underestimate their actual recall on EOL; 6-year-old children exhibit accurate monitoring on EOL, JOL and JOC.