It was erected as an apostolic vicariate on 9 April 1920, with territory taken from the mission of Canton, and was entrusted to the Salesian Society of St John Bosco, which, for missionary work, sends members of the religious registered with the regular Chinese province based in Macao. On 11 April 1946, with the establishment of the episcopal hierarchy in China, it was raised to the status of a suffragan diocese of Canton. It covers an area of 34,500 sq km. As of 30 June 1949, out of a total population of approximately 2,500,000, there were 5,205 Catholics and 283 catechumens; there were 7 Chinese secular priests and 18 Salesian priests. The auxiliary personnel consisted of 2 Salesian lay brothers, 10 Daughters of Mary Help of Christians, and 18 Chinese religious sisters, 24 catechists, and 74 teachers. The works included 20 dispensaries, 2 orphanages, 1 hospice for the elderly and 1 for the blind, 14 churches, and 21 chapels scattered across the territory, which was divided into 11 districts with 17 primary stations and 26 secondary ones. The 19 elementary schools had 2,344 pupils, the secondary school 197, the vocational school 11, the catechist school 7, and the 6 prayer and elementary schools had 122 listeners.
The first Christian preaching in Shiu'Chow dates back to Fr Matteo Ricci, who resided in this city after being expelled from Shihling in 1589; he was followed by French and Portuguese Jesuits. In the mid-19th century, the entire province of Kwangtung passed to the Paris Foreign Missions Society, which in Shiu'Chow was succeeded by the Salesians, who arrived on the scene in 1918. Mgr Luigi Versiglia, assassinated on 25 February 1930 together with his young missionary companion Fr Caravario, was the first apostolic vicar of Shiu'Chow.