Abstract: A spherical sundial is designed by application of the relations between different celestial coordinates and the projection principle of the sundial, which is the product of a successful combination of equatorial sundial, gnomon and modern precision astronomical measurement. Since the time measured with sundial is the local apparent solar time, the Beijing local apparent time can be easily worked out by adjusting directly the time on the dial face according to the relation between the longitude and time differences, and after a mean move-out correction, the Beijing time can thus be determined. At the same time, through the analysis of the yearly recurrent motion of the sun, the solar term lines are set and the exact date of the day can be decided by observing the sundial needle tip’s projection location on the surface of the sundial against the solar term lines.