Objective: To observe the imaging appearances of ultrasound in papillary thyroid microcarcinoma(PTMC), correlated with the histopathologic findings. Methods: The US results from 106 cases of PTMC with 122 nodules and correlated the results with the histopathologic findings were retrospectively evaluated. Results: The 63.9% of the PTMC nodules had an ill-defined boundary and the remaining had a well-defined boundary. A few(2.5%) of the PTMC nodules had a cystic element. The 30.3% of the nodules had a halo sign. Microcalcification was present in approximately half of the PTMC nodules. The rate of ultrasonic elastography(UE)≥3 is 60%. The amount of papillary structure and the fibrous stroma in the cancerous tissue determined the echogenicity of the nodule. A halo sign with a well-defined boundary was associated with the presence of an intact fibrous pseudo-capsule. Psammoma bodies were detectable on US as microcalcifications. Conclusion: The ultrasound findings of PTMC are correlated with its histopathological category. The “ill-defined boundary”, “hypoecho”, “microcalcification”, “ultrasonic elastography(UE)≥3” are useful for the diagnosis of PTMC.