Benefitted from the strong compatibility and scalability, Hf0.5Zr0.5O2 (HZO) based ferroelectric field-effect transistor (FeFET) has gained extensive attention as artificial neuron and synapse. In this work, with in-depth understanding of the correlations between domain switching (DS) and charge trapping (CT), multi-states in FeFET are controlled precisely by modulating the channel conductance. When DS contribution dominates, cycle-to-cycle variations can be well suppressed in the intermediate storage states. With further co-optimizations by including CT and temperature impacts, symmetric linear conductance modulations and large conductance ratios are achieved simultaneously. The biological synaptic potentiation and depression characteristics demonstrate the great potential of HZO FeFET in neuromorphic computing.