As the conductivity gradually changes in hysteresis of transfer characteristics curves, the field-effect transistors (FETs) exhibit a dependent memory behavior, which is analogue to the transmission properties of the biological synapses. The channel in FETs memory is the transmission route of the carriers, which determines the device mobility and further affects the memory window and operating speed. Here, we investigate the hysteresis effect in Dinaphtho [2, 3-b: 2’, 3’-f] thieno [3, 2-b] thiophene (DNTT) thin-film transistor through the different morphologies' semiconductor. The maximum memory window in our organic transistor is up to 38.6 V at the evaporation rate of 0.01 nm/s, which is comparable with the previously reported bipolar synaptic transistors. This difference in hysteresis effect can be attributed to the void and grain boundarie in semiconductor channel hindering the transmission of charge carrier, thereby hindering the memory behaviour. This work provides evidence for demonstrating the influence of organic semiconductor on the hysteresis of field-effect transistor, and also presents the application prospect of organic transistor in artificial intelligence and neural computing system.