Best focus approach of HinOTORI telescope

HinOTORI is a 50cm telescope which is co-constructed and shared by China and Japan. It can image in u’, Rc and Ic bands simultaneously, its main scientific observation targets are gravitational waves (GWs) optical counterparts (OTs). The installation of the telescope has been finished, and the engineering first light observation was carried out in May 2018. This paper will give an overall introduction and parameters of the telescope and then concentrate on a focusing method, which aims at obtaining the best focus position from the fitting equation. The reason of the best position shifting is also discussed.