Objective: To analyze the diagnostic value of transvaginal ultrasound combined with serum beta-human chorionic gonadotropin (β-hCG) for ectopic pregnancy with small-diameter ( ≤ 4 cm) solid masses. Methods: A total of 60 patients with suspected ectopic pregnancy who were admitted to the hospital from January 2022 to June 2025 were reviewed. All patients underwent transvaginal ultrasound examination and their β-hCG levels were detected. According to surgical and pathological results, patients were divided into the ectopic pregnancy group (35 cases) and the normal pregnancy group (25 cases). The diagnostic efficiency of transvaginal ultrasound was analyzed, and β-hCG levels in the two groups were compared. The diagnostic value of transvaginal ultrasound combined with β-hCG for ectopic pregnancy with solid mass ≤ 4 cm in diameter was analyzed. Results: Transvaginal ultrasound diagnosed 33 cases with ectopic pregnancy and 27 cases without. Compared with the gold standard, the diagnostic sensitivity, specificity, accuracy, positive and negative predictive values were 85.71%, 88.00%, 86.67%, 90.91% and 81.48% respectively (Kappa value = 0.729). β-hCG level in the ectopic pregnancy group was lower than that in the normal pregnancy group (P<0.05). ROC analysis showed that the AUC values for diagnosing ectopic pregnancy using transvaginal ultrasound and β-HCG alone were 0.869 (0.756~0.942) and 0.800 (0.677~0.892), respectively. The AUC value of combined diagnosis was 0.967 (0.885~0.996), significantly higher than that of transvaginal ultrasound and that of β-HCG (Z=2.677, 2.727, P<0.05). Conclusion: Transvaginal ultrasound combined with β-hCG demonstrates high diagnostic efficacy for ectopic pregnancy with solid mass ≤ 4 cm in diameter.