The purpose of this study were (a) to examine the effectiveness of a computer simulation program (Computer Simulation for Teaching Critical Thinking on Gender Equality, CSTCT-GE) on preservice teachers¡¦ improvement in professional knowledge for teaching critical thinking and teaching efficacy for critical thinking; and (b) to examine the effects of gender, educational degree, critical-thinking ability, motivation for professional growth, and level of training involvement on preservice teachers¡¦ increase in professional knowledge and teaching efficacy for critical thinking. A one-group pretest-posttest design was employed in the study. Seventy-two preservice teachers participated in the study. The employed instruments were Computer Simulation for Teaching Critical Thinking on Gender Equality (CSTCT-GE), The Test for Professional Knowledge in Teaching Critical Thinking, The Test for Teaching Efficacy in Critical Thinking, the Test of Critical-thinking Skills for Adults, and The Test of professional growth for Junior High School Teachers. The applied analysis methods were descriptive statistics, Hotelling¡¦s T2, repeated measures of variance, multivariate analysis of covariance, and multiple stepwise regression. The main findings of this study were as follows: 1. CSTCT-GE was effective in improving the preservice teachers¡¦ professional knowledge and teaching efficacy for critical thinking. 2. The preservice teachers¡¦ increase of professional knowledge did not have significant effects on their enhancement of teaching efficacy for critical thinking. 3. There were no significant gender and educational degree effects on the preservice teachers¡¦ improvement of professional knowledge and teaching efficacy for critical thinking. 4. There were no significant critical-thinking ability effects on the preservice teachers¡¦ enhancement of teaching efficacy for critical thinking. 5. There were no significant professional growth motivation on the preservice teachers¡¦ improvement of professional knowledge and teaching efficacy for critical thinking. 6. The preservice teachers¡¦ level of training involvement had positive effects on their increase of professional knowledge for teaching critical-thinking but not on their enhancement of teaching efficacy for critical thinking. 7. The preservice teachers¡¦ level of training involvement could effectively predict their professional knowledge for teaching critical thinking in the posttest. 8. The preservice teachers¡¦ level of professional growth motivation could effectively predict their teaching efficacy for critical thinking in both the pretest and the posttest. Finally, the researcher proposed some suggestions for educational organizations, preservice teachers, inservice teachers, and future studies.