Objective To explore the clinical value of transthoracic contrast echocardiography（cTTE） ，contrast transesophageal echocardiography（cTEE） in the diagnosis of pulmonary arteriovenous malformation（PAVM）.Methods 50 suspected PAVM positive patients in our hospital were selected and all underwent cTTE and cTEE examinations to observe the time and number of microvesicles in the left heart cavity, and semi quantitative grading was performed. Using chest computed tomography or computed tomography pulmonary angiography（CTPA）results as diagnostic criteria, draw receiver operating characteristic (ROC) curves to analyze and compare the diagnostic efficacy of cTTE and cTEE for PAVM; Use logistic regression to analyze the relationship between cTTE, cTEE semi quantitative grading, and chest CT or CTPA diagnosis of PAVM. Results Of the 50 suspected PAVM-positive patients who underwentchest CT/CTPA examinations simultaneously，6 were positive for PAVM and 44 were negative for PAVM.The results of cTTE semi-quantitative classification showed that there were 1 case of grade I, 1 case of grade II and 4 cases of grade III in PAVM group. The results of cTEE semi-quantitative grading showed that there were 1 case of grade Ⅱ and 5 cases of grade Ⅲ in PAVM group. The cTTE semi-quantitative grading and cTEE semi-quantitative grading in PAVM group were higher than those in non-PAVM group, and the differences were statistically significant (P < 0.05). ROC curve analysis showed that the sensitivity，specificity and area under the curve (AUC) of cTTE in diagnosing PAVM were 66.7% 、86.4% and 0.814,，respectively，which were lower than cTEE（83.3%、88.6% and 0.890），and the differences were statistically significant（P＜0.05）.Logistic regression showed that the risk of PAVM was 12.865 times higher in patients with cTTE high-risk grade (cTTE semi-quantitative grade > Ⅱ) than in patients with low risk grade (cTTE semi-quantitative grade ≤Ⅱ) with semi-quantitative grade > Ⅱ as the cut-off value for diagnosis of PAVM. The risk of PAVM in high-risk cTEE patients was 39.450 times that of low-risk CTEE patients (P < 0.05), and the difference was statistically significant. Conclusion For suspected PAVM positive patients，the detection rate of cTEE is superior to cTTE；Even if there are microbubbles in the early left ventricular cavity during cTTE and cTEE examinations，the presence of PAVM should be carefully considered；For suspected PAVM positive patients after cTTE and cTEE screening，when cTEE semi-quantitative grading is level Ⅲ，further improvement of chest CT/CTPA examination can reduce unnecessary radiation exposure.