Abstract: Objective To study the diagnostic value of high frequency ultrasound for thyroid microcarcinoma(TMC). Methods Characteristics of 2D ultrasound and color Doppler blood flow imaging(CDFI)for 84 patients(112 nodules) were retrospectively analyzed. Results The accurate diagnosis rate of ultrasound was 86.9%(73/84)for TMC before operation.Of the 112 nodules,98(87.5%) were low echo nodules,82(73.2%) were irregular nodules,74(66.1%) had fuzzy or spicule-like boundaries,60(53.6%)showed microcalcification foci.The ultrasound findings in some tumor bodies were significantly different from those described above.The CDFI findings showed that typesⅡandⅢblood flow signals accounted for 66.1%(74/112).The mean value of maximal systolic blood flow velocity(Vmax)and resistance index(RI)measured by pulse Doppler were 21.2cm/s and 0.72,respectively.The metastatic rate of neck lymph node carcinoma was 22.6%(19/84). Conclusion High frequency ultrasound is the first choice of method for the diagnosis of TMC.Single ultrasound characteristics and CDFI findings are limited for the diagnosis of neck TMC.Attention should be paid to "different imaging of the same disease and identical imaging of a different disease" in differential diagnosis of TMC.