Huang Yizi is the first person to be jailed for opposing Zhejiang province's intense campaign to remove crosses from churches.
Authorities in the province tore down about 400 rooftop crosses last year, saying they violated the building code.
Churchgoers and religious rights advocates say the Christian faith is being targeted because its rapid growth unnerves the ruling Communist Party.
After a six-hour trial, a court in the city of Pingyang found Huang guilty of gathering crowds to disrupt social order, lawyer Zhang Kai said by telephone.
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Huang, an outspoken pastor, was taken away by police last summer after he brought some parishioners to a local government building to demand answers about a July clash in which security personnel armed with sticks attacked congregation members who had been keeping a night vigil over the cross atop their sanctuary.
Huang also urged local church leaders to put back the toppled crosses.
Zhang said the charge stemmed largely from the gathering in front of the government building, but said Huang did not disrupt social order and instead played a mediating role.