Background: Cleft lip and palate is one of the most common oral and maxillofacial deformities associated with a variety of functional disorders. Cleft palate speech disorder (CPSD) occurs the most frequently and manifests a series of characteristic speech features, which are called cleft speech characteristics. Some scholars believe that children with CPSD and poor speech outcomes may also have weaknesses in speech input processing ability, but evidence is still lacking so far. Aims: (1) To explore whether children with CPSD and speech output disorders also have defects in speech input processing abilities; (2) to explore the correlation between speech input and output processing abilities. Methods & Procedures: Children in the experimental group were enrolled from Beijing Stomatological Hospital, Capital Medical University, and healthy volunteers were recruited as controls. Then three tasks containing real and pseudo words were performed sequentially. Reaction time, accuracy and other indicators in three tasks were collected and then analysed. Outcomes & Results: The indicators in the experimental group were significantly lower than those in the control group. There was a strong correlation between speech input and output processing tasks. The performance of both groups when processing pseudo words in the three tasks was worse than that when dealing with real words. Conclusions & Implications: Compared with normal controls, children with CPSD have deficits in both speech input and output processing, and there is a strong correlation between speech input and output speech processing abilities. In addition, the pseudo words task was more challenging than the real word task for both groups.