This study aims to explore the changes of left atrial function in patients with cardiac amyloidosis (CA) by speckle tracking echocardiography (STE) and identify the difference of left atrial properties between patients with CA and those with hypertrophic cardiomyopathy (HCM). In this study, 16 patients with CA, 16 patients with HCM, and 16 age-matched healthy controls were enrolled. The time-dependent strain parameters (LASr, LAScd, and LASdt) and strain rate parameters (m-SRs, m-SRe, and m-SRa) of left atrial function were measured by STE in patients with CA, then were compared with that in patients with HCM. Compared with the control group, CA group showed significantly reduced LVEDV/BSA, LVESV/BSA, A, and GLS of the left ventricle, and significantly increased heart rate, IVSd, IVPWd, E, E/A, E/e', LAd and LAV/BSA. The left atrial reserve (LASr and m-SRs), conduit (LAScd and m-SRe) and pump (LASdt and mSRa) functions of CA group were significantly reduced compared with that of controls (P<0.05). The left atrial reserve and pump functions of CA group were significantly reduced compared with that of HCM group. In the CA group, the left atrial reserve function (LASr and m-SRs), conduit function (LAScd and m-SRe) and pump function (LASct and m-SRa) were all related to left ventricular GLS and E/e'. The reserve function, conduit function and pump function of left atrial in the CA group decreased significantly than that in the health control group. When comparing with HCM group, CA group showed reduced reserve function and pump function of left atrial. STE is a qualified technique for the diagnosis of CA.