Word semantic knowledge (WSK) is crucial to the development of one's reading comprehension ability. A total of 608 students (208 poor readers in the experimental group and 200 poor readers in the control group one, and 200 typical readers in control group 2) from grade 4 participated in this study. Selected reading ability assessments were administered at pretest, post-test and a 3-month delayed post-test. After 6 weeks of intervention, poor readers from the experimental group scored higher in Chinese reading abilities than the poor readers in control group one. Experimental group students reached a similar level of reading abilities with typical readers. Findings from this study suggested the main challenge in reading activities for those students who had reading problems is the characters' semantic identification. The current study confirmed the self-agency learning mode is an effective approach to semantic intervention design on semantic network construction for primary school learners.