This study aims to explore whether Guzheng playing training has a positive impact on the brain functional state of children with Autism Spectrum Disorder (ASD) based on power spectral and sample entropy analyses. Eight ASD participants were selected to undergo four months of Guzheng playing training, with one month as a training cycle. Electroencephalogram (EEG) signals and behavioral data were collected for comparative analysis. The results showed that after Guzheng playing training, the relative power of the alpha band in the occipital lobe of ASD children increased, and the relative power of the theta band in the parietal lobe decreased. The differences compared with typically developing (TD) children were narrowed. Moreover, some channels exhibited a gradual increase or decrease in power with the extended training period. Meanwhile, the sample entropy parameter also showed a similar upward trend, which was consistent with the behavioral data representation. The study shows that Guzheng training can enhance the brain function of ASD patients, with better effects from longer training. Guzheng playing training could be used as a daily intervention for autism.