The study plant was autotetraploid ‘Han Fu’ apple,which was doubled by colchicin from a diploid.The leaves of autotetraploid and diploid plants were compared by using the methods of paraffin section,scanning electron microscopy(SEM) and chlorophyll fluorescence parameters diurnal fluctuations.The results showed that:(1)The thickness of leaf,the P/S,the length of stoma,the width of stoma,the number of chloroplasts per guard cell pair and the content of chlorophyll of autotetraploid were increased by 15.1%,16.1%,70.5%,27.2%,125.3% and 37.7%,but the density of stomata was decreased by 58.7% than that of diploid.The different was significant.The variation tendency of F_v/F_m,F_v/F₀ and PI value were similar.The average performance index (PI) value in autotetraploid apple was increased by 38.6% than that of diploid.So,the leaves of autotetraploid were more big,more thick.The stomata were more bigger and the stoma density was more smaller.It suggested the autotetraploid had better disease resistance and photosynthetic performance than that of diploid.