〔Abstract〕 Objective To explore the value of vector angle of Lorenz plots(LPs) and the role of combining B-line slope in improving the diagnostic efficiency of arrhythmia. Methods LPs of 119 cases with ventricular premature contraction(VPC group), 97 cases with supraventricular premature contraction(SPC group), 52 cases with type II°I atrioventricular block(Ⅱ°Ⅰ group) and 54 cases with type Ⅱ°Ⅱ atrioventricular/sinoatrial block(Ⅱ°Ⅱ group) were retrospectively analyzed. The B-line slope and vector angle were measured, and the differences between groups were compared. Receiver operating characteristic curve was used to analyze the diagnostic efficacy of B-line slope, vector angle and their combination between groups, and MedCalc software was used for statistical comparison. The consistency of intra-observer and inter-observer measurements of B-line slope and vector angle was evaluated using Intra group correlation coefficient(ICC) and Bland-Altman plot. Results There were significant differences between VPC group and SPC group, and between Ⅱ° Ⅰ group and II°II group(P<0.05).The area under the curve(AUC) of B-line slope, vector angle, and the combination of the two in distinguishing ventricular and supraventricular premature contraction were 0.81,0.84 and 0.87 respectively, and the AUC in distinguishing type Ⅱ°Ⅰ and type Ⅱ°Ⅱ atrioventricular/sinoatrial block were 0.76, 0.78 and 0.80 respectively. The ICC of vector angle was better than B-line slope(Intra-observer 0.99vs0.98, Inter-observer 0.97vs0.96). Conclusion Vector angle can be used to identify the type of arrhythmia, and has good intraobserver and interobserver consistency. Its combination with B-line slope has the highest accuracy in diagnosing arrhythmia, providing a new reference for clinical diagnosis and treatment.