Objective To explore the effects and possible mechanism of Lianxia Ningxin Formula（连夏宁心方） in treatment of ventricular arrhythmia（VA）. Methods Forty-eight healthy male SD rats were randomly divided into blank group

model group

Wenxin Granule（稳心颗粒） group

and Lianxia Ningxin Formula low

medium and high dose groups

with eight rats in each group. Wenxin Granule at 1.75 g/（kg·d） was given by gavage to the Wenxin Granule group

while Lianxia Ningxin Formula at 0.68

1.35 and 2.71 g/（kg·d） were administered by gavage in the corresponding low

medium and high dose groups; normal saline at 1.0 ml/100 g was given by gavage to both the blank group and the model group. After 21 days of administration

rats in all groups but the blank group were injected with adrenaline through the sublingual vein to develop VA model. The standard Ⅱ lead electrocardiogram of the limbs was recorded; the occurring time of ventricular premature beats（VP） and ventricular tachycardia（VT）

and the lasting time of VT within 15 minutes after modeling were assessed. Western blotting was used to detect the protein content of cardiac tissue calmodulin（CaM）

calcium/calmodulin-dependent protein kinase Ⅱ（CaMKⅡ） and ryanodine receptor 2（RyR2） in myocardial tissue. Results Compared to the blank group

the model group had significantly increased CaM and CaMKⅡ protein expression and decreased RyR2 protein expression in the myocardial tissue（P<0.05 or P<0.01）. Compared to the model group

Wenxin Granule group postponed the occurring time of VT and shortened the lasting time of VT

reduced the CaM and CaMKⅡ protein expression

and increased RyR2 protein expression in the myocardial tissue（P<0.05 or P<0.01）. Lianxia Ningxin Formula high dose group had prolonged the occurring time of VP and down-regulated the CaM protein expression（P<0.05）; Lianxia Ningxin Formula low and medium dose groups significantly delayed the occurring time of VP and VT

shortened the lasting time of VT

decreased CaM and CaMKⅡ protein expression

and increased RyR2 protein expression（P<0.05 or P<0.01）. Compared to those in the Lianxia Ningxin Formula high dose group

the expression of CaM protein in myocardial tissue was significantly decreased

and the expression of RyR2 protein was significantly increased in the low

medium dose groups and Wenxin Granule group（P<0.05 or P<0.01）. Conclusion Lianxia Ningxin Formula may achieve antiarrhythmic effects by down-regulating the expression of CaM and CaMK Ⅱ and up-regulating the expression of RyR2 in the myocardial tissue

and the low and medium doses have better effects.