The purpose of this study was to understand the relationships between multiple intelligences, thinking styles, and critical-thinking abilities of the fifth- and sixth-grade students. Investigation method was employed in the study. 578 fifth- and sixth-grade students in the suburban and urban areas of Tainan and Kaohsiung participated in this study. The employed instruments included Multiple Intelligences Appraisal, Thinking Styles Appraisal for the Primary Students, and the Test of Critical-thinking Skills for Primary and Secondary School Students. The applied analysis methods were Descriptive Statistics, Hotelling¡¦s , Multivariate Analysis of Variance, Canonical Correlation Analysis, and Discriminant Analysis. The main findings of this study were as follows: 1. There were no significant gender differences in critical-thinking abilities. 2.The students¡¦ critical-thinking abilities in urban areas were better than those in suburban areas. 3. The students¡¦ logical-mathematical intelligence and linguistic intelligence were positively correlated with their abilities of making deductions and evaluating arguments. 4. There were no significant differences in critical-thinking abilities for students with different level of executive thinking style. 5. There were significant differences in critical-thinking abilities for students with different level of legislative thinking style. 6. There were significant differences in critical-thinking abilities for students with different level of judicial thinking style. 7. The students¡¦ living areas, logical-mathematical intelligence, linguistic intelligence, and judicial thinking style were positively correlated with their abilities in recognizing assumptions, making deductions, and evaluating arguments. Finally, the researcher proposed some suggestions for the educational organizations, the primary school teachers, and future studies.