The purpose of this study were to examine the discrepancies in metacognitive ability and critical thinking ability between gifted students in terms of their grade and gender. This study use two-way multivariate analysis of variance was applied to analyze the discrepancies in metacognitive ability and critical thinking ability. The main finding of this study were as follows: 1. Female gifted students and male gifted students don't have the differences in metacognitive abilities; junior high school gifted students superior to elementary school gifted students in part of their metacognitive abilities, junior high schools' and elementary schools' of female gifted students and male gifted students don't have interaction in metacognitive abilities. 2. (1). Junior high school gifted students were superior to elementary school gifted students in terms of all critical thinking; (2). Female students and male gifted students don't have the differences of critical thinking abilities; (3). Junior high schools' and elementary schools' of female gifted students and male gifted students don't have interaction in critical thinking abilities. 3. A Canonical Correlation existed between metacognitive ability and critical thinking abilities. 4. Metacognitive ability can be used to predict critical thinking abilities of gifted students. And critical thinking ability can be used to predict Metacognitive abilities of gifted students too. Further discussion was made on the basis of the these findings and some suggestions on teaching and future research were offered.