This case study examined the effect of a lingual control therapy based on motor learning principles in a 5; 30-year-old monolingual Putonghua-speaking girl with functional speech sound disorder (SSD). The participant received 1240-minute individual therapy sessions once a week over 6 months, wherein the spatiotemporal instruction for lingual training integrating auditory and visual feedback was given. Fisher's exact test and linear regression model were fitted to examine the differences in response accuracy between time points. The accuracy of training-(at phoneme and syllable level) and test-probes (at word and sentence level) both demonstrated positive change, indicating generalization of the treatment gains to larger linguistic units. Additionally, the place of articulation was found to mediate the treatment outcomes based on the linear regression with interaction results. Finally the possible underlying deficits in internal speech processing mechanism of the tongue musculature and the corresponding implications are explored. Findings from this study suggest that training in lingual motor control could improve distorted syllable-initial apical consonants in Putonghua-speaking children with SSD. Future research should investigate the generalization effect in a larger sample size.