To study the behavioral characteristics and changes in DARPP-32 phosphorylation level in the striatum of the levodopa/carbidopa and levodopa/carbidopa/entacapone-induced dyskinesia rat model. Methods: Twenty-nine Parkinson’s disease rat models were successfully established then randomly divided into four groups. The normal saline (NS) group included 5 rats, and the levodopa/carbidopa (LC) group, entacapone equivalent dose (LCE) group, and entacapone additional dose (LCE+) group each included 8 rats. Rats in each group were given intragastric administrations of the corresponding drugs for 28 days. Rat behavior was observed on the 1st, 4th, 8th, 12th, 16th, 20th, 24th, and 27th day after drug administration. Changes in DARPP-32 phosphorylation level in the striatum were measured by western blot technique. Results: The abnormal involuntary movement (AIM) scores of the LCE group and LC group were respectively (21.7±10.2) and (22.2± 11.1) points, the difference showing no statistical significance (P>0.05), and the difference between the AIM scores of the two groups at each measured timepoint showed no statistical significance (P>0.05). The AIM score of the LCE+ group was (28.6±14.9) points, and this was higher than that of the LCE group and LC group (both P<0.05). Starting with the 8th day of drug administration, the AIM score of the LCE+ group began surpassing that of the LC group and LCE group (both P<0.05). The LCE, LCE+, and LC groups showed a higher lesion-side DARPP-32 phosphorylation level than that of the non-lesion side of all groups (all P<0.05). The LCE+ group showed a higher lesion-side DARPP-32 phosphorylation level than that of the NS, LCE, and LC groups (P< 0.05). The LCE group and LC group lesion-side DARPP-32 phosphorylation levels displayed no significant difference (P>0.05). Conclusion: The addition of entacapone to levodopa treatment under equivalent dose conditions results in neither deterioration nor relief of dyskinesia.