Abstract: To detect the function and expression of ventricular M₃ receptor (M₃R) in cerebral-cardiac syndrome (CCS) model rats and to explore the relationship between the expression of M₃R and the arrhythmia resulted from CCS, CCS model rats were induced by occluding right middle cerebral artery. ECG was monitored. Intracellular calcium (［Ca²⁺］_i) changes after agitating M₃R were recorded by laser scanning confocal microscope. Changes of M₃R expression in the ventricular tissue were detected by Western blotting. QRS and QT intervals in CCS group were remarkably longer than that in sham group. According to the results of Western blotting， the level of M₃R expression was remarkably lower in CCS group compared with that in the normal group. KCl induced ［Ca²⁺］_i increasing in CCS group could be depressed by choline and the effect of choline could be blocked by 4-DAMP. The lower expression of M₃R in CCS group may be one of important reasons of arrhythmia resulted from CCS. M₃R that depressed the ［Ca²⁺］_i increasing agitated by choline may become a new target to cure arrhythmia resulted from CCS.