Objective: To explore the electrocardiogram waveform characteristics and diagnostic value of fetal arrhythmia. Methods: The clinical data of 64 pregnant women who underwent fetal electrocardiogram examination during prenatal examination in our hospital from March 2022 to June 2025 and were clinically diagnosed with fetal arrhythmia were retrospectively collected and included in the case group. Meanwhile, the clinical data of 64 pregnant women with normal intrauterine pregnancies who underwent fetal electrocardiogram examination in the hospital during the same period were collected 1:1 and included in the control group. Observe the waveform characteristics of the fetal electrocardiogram and analyze the diagnostic value of the electrocardiogram waveform characteristics for fetal arrhythmia. Result: Electrocardiogram examination shows that compared with normal fetuses, the electrocardiogram of fetal arrhythmia has changes in the frequency, rhythm and morphological characteristics of QRS waves. The tachycardia type is characterized by an increased frequency of QRS waves, regular rhythm and normal morphology. Bradycardia type is characterized by a slowed QRS wave frequency, regular rhythm and normal morphology. Premature beats are characterized by the early appearance of QRS waves, followed by a complete or incomplete compensatory period. The results of diagnosing fetal arrhythmia by electrocardiogram waveform characteristics were in good consistency with the clinical diagnosis results (Kappa=0.891, P < 0.001). The sensitivity, specificity, accuracy, positive predictive value and negative predictive value were 93.75%, 95.31%, 94.53%, 95.24% and 93.85% respectively. The classification results of fetal arrhythmia diagnosed by electrocardiogram waveform characteristics were in good consistency with the clinical diagnosis results (Kappa=0.876, P < 0.001). The overall accuracy rate of differential diagnosis was 92.19%. Conclusion: The electrocardiogram waveform characteristics of fetal arrhythmia are relatively typical, and the electrocardiogram waveform characteristics have high diagnostic value for fetal arrhythmia. They can differentiate and diagnose different types of fetal arrhythmia and are highly consistent with the comprehensive clinical diagnostic results.