毕方济（Francesco Sambiasi，1582年 - 1649年），耶稣会传教士，意大利人，精于天文数学，1610年来华，先抵达澳门，1613年进入北京，后去淮安、南京、无锡、上海嘉定传教，曾在南京城内兴建护守山圣堂。南明永历帝封他为太师。著有《毕方济奏摺》、《灵言蠡勺》（毕方济口授，徐光启笔录）、《天学略义》。

Francesco Sambiasi (1582 in Cosenza, Calabria, Italy – January 1649 in Kanton, China), known as Bi Fangji (毕方济) in Chinese, was a Catholic missionary to China, part of the Jesuit missions there. He was sent with the boat Nossa Senhora da Piedade to the East on 23 March 1609 and arrived in Macau in 1610. He worked in various places during his mission in China: Beijing (1613–1616), Jiading and then Shanghai (1622), a stint in Korea, then to Kaifeng (1628), Shanxi, Shandong, Nanjing (1631–1643) and then to Macau ("patente de Embaixador", 1645).

In the summer of 1645, he was appointed as the ambassador to Macau by the Southern Ming Hongguang Emperor, and was sent to petition for military aid from the Portuguese colony there.

In 1646 he worked for the Yongli Emperor as a "folk master" and the year after as a mandarin.

During his time in Nanjing, at the efforts of Xu Guangqi, Sambiasi was appointed to the Imperial Astronomical Bureau. In this role, he was made responsible for the correction of the calendar, and the observation of eclipses.