The invention discloses an autoclave curing process of a fiber cement board. The process includes the following steps: increasing autoclave temperature from 0 DEG C to 100 DEG C under the pressure of0 Pa; during a first period, simultaneously increasing the autoclave temperature and autoclave pressure twice, increasing the autoclave temperature from 100 DEG C to first autoclave temperature, and increasing the autoclave pressure from 0 Pa to first autoclave pressure; during a second period, keeping the first autoclave temperature and the first autoclave pressure for autoclave; during a third period, simultaneously reducing the autoclave temperature and the autoclave pressure twice, recovering the autoclave temperature to 100 DEG C, and recovering the autoclave pressure to 0 Pa. The beneficial effects of the process are that the temperature is increased/ reduced according to time nodes, and the autoclave temperature and the autoclave pressure at each time node are strictly controlled soas to make the autoclave temperature and the autoclave pressure match each other, thereby reducing the brittleness coefficient of cement, reducing the probability of crack of the cement board, and greatly increasing the production qualified rate of the fiber cement board.