Self-talk is a widely used self-regulation strategy in sport psychology, but it is unclear whether children can benefit from self-talk strategy. The present study (2 x 3 design) examined whether low-grade children in primary school can benefit from self-talk intervention. 88 students (47 males, 41 females, Mage = 7.5 years old) were randomly divided into three groups for elbow plank task, the: motivational self-talk group (n = 30), instructional self-talk group (n = 29) and control group (n = 29). One-way ANOVA revealed that the percentage of improvement in the motivational self-talk group was significantly higher than the instructional self-talk group and the control group while there was no difference between the latter two groups. Additionally, repeated measures ANOVA revealed a significant trial by group interaction effect in the willingness to continue elbow plank. Pairwise comparisons revealed that motivational self-talk group improved whereas performance of the other two groups did not change significantly. Motivational self-talk is more effective for young children.