Objective To evaluate theleft ventricular diastolic and systolic function in patients with sick sinus syndrome (SSS) with or without paroxysmal atrial fibrillation (PAF) by speckle tracking imaging combined with pressure strain loop. Methods A Total of 37 PSS cases were selected as SSS group， 25 cases of PSS combined with PAF as SSS with PAF group，30 healthy subjects as control group.The left and right atrial diameters (LA and RA) ，end-diastolic and -systolic diameters (LVEDs and LVEDd) ，peak velocity of early and late diastolic mitral valve(E and A) ，isovolumic diastolic time (IVRT) ， mitral E-peak deceleration time (EDT)， and early diastolic peak velocity (e'') of mitral annulus were measured by conventional echocardiography， E/A and E/e'' were calculated.The left ventricular myocardial strain and work parameters were measure，including global longitudinal strain (GLS)，peak-time dispersion (PSD) ，global work index（GWI)，global work efficiency (GWE) ，global constructive work (GCW)， global wasted work (GWW).And the peak twist(Ptw)，peak twist velocity(PTV)，peak untwisting velocity(PUV)，untwisting rate(UntwR) were measured.Results ①Compared with the control group， RA，E/e’，IVRT and Ptw、PTV of globe and apical segment，PSD，GWW in SSS group were increased，while UntwR，PUV，GWI of basal segment were decreased(all P<0.05).RA，LA，LVEDs，LVESd，E/e’ and IVRT in SSS with PAF group were increased，while Ptw、PTV、UntwR、PUV of globe and basal segment，and GWI，GCW were decreased(all P<0.05). ②Compared with SSS group，LA，LVEDd，LVESd，IVRT，PSD，GWW in SSS with PAF group were increased，LVEF，EDT and Ptw，PTV，PUV of globe and each segments were decreased，global UntwR，GLS，GWI，GCW，GWE were also decreased(all P<0.05).Conclusion Speckle tracking imaging combined with pressure strain loop can early and quantitatively evaluate the early damage and the degree of left ventricular diastolic and systolic function in SSS combined with PAF patients.