The invention relates to the technical field of ceramic production, in particular to a manufacturing process of ceramic with low porosity. The manufacturing process comprises the following steps: (1) raw materials of a ceramic green body are mixed uniformly and sufficiently in a high-speed mixer, and then the mixture is placed in a vacuum tank for air removal; (2) the ceramic green body is shaped, aired and washed finely; (3) the ceramic green body is biscuited at the temperature of 850-900 DEG C for 5-10 min, then soaked in an impregnation liquid containing carbon powder and nanometer aluminium oxide for 20-30 s, taken out, drained and biscuited at the temperature of 850-900 DEG C for 5-10 min, and soaking and biscuiting are repeated 2-3 times; (4) glazing is performed; (5) glaze firing is performed under the conditions of temperature being1300-1500 DEG C and pressure being 0.5-2.5 Mpa, heat is preserved for 4-8 h, natural cooling is performed, and the ceramic product with low porosity is obtained. By means of repeated soaking and biscuiting, the quantity and the size of pores in the ceramic green body are reduced, and reduced porosity of the finished ceramic product is guaranteed; improvements are made on the basis of the traditional ceramic manufacturing process, the ceramic manufacturing cost is controlled, and benefits are provided for both manufacturers and customers.