Research Findings: Low-socioeconomic status (SES) (intervention group, n = 31; control group, n = 32) and middle/high-SES (reference group, n = 33) 5-year-old Chinese kindergartners were screened through SES and IQ test. Their number sense was examined over five time points. The pretest was conducted at the beginning of the fall semester, followed by three immediate posttests monthly. Math play training was administrated to the intervention group and story reading to the other two groups during this time. Lastly, a delayed posttest was conducted two months later after the last immediate posttest. All the interventions were carried out in small groups, 15-30 minutes sessions, 2 days per week for 12 weeks. The promotion effect of math play training was monitored based on response to intervention (RtI) paradigm. Utilizing latent growth modeling, we found that the intervention group got significant improvement in number sense and almost caught up with the middle/high-SES group after training, and the intervention effects persisted for two months. The control group had the slowest rate of progress and significantly lower scores than the other two groups. Practice or Policy: RtI-based mathematical game intervention could improve the number sense level and growth rate of preschoolers in rural areas.