The invention discloses a preparation method of a large-size sintered silicon carbide wear-resistant pipeline, which comprises the following steps: earlier-stage molding, slurry mixing and slip casting, later-stage sintering and earlier-stage molding. The method specifically comprises the following steps that (1) a production drawing is processed, (2) an outer bottom die is manufactured, (3) an inner bottom die is manufactured, (4) the outer bottom die is used for manufacturing the production outer die, (5) a production inner die is manufactured, and (6) the production inner die is used for manufacturing the inner die. After the sizes of the production units are obtained after a drawing is analyzed, production is conducted according to the production units, then splicing is conducted, andthe large-size sintered silicon carbide abrasion-resistant pipeline can be obtained. The method is simple in overall process, the content of the dispersing agent and the content of the binding agent are increased in the slurry, blank forming can be promoted, and therefore the problem that a large-size pipeline is prone to cracking is solved. According to the technology, a traditional production process is completely changed, a two-mold-opening structure is adopted, and a positioning assembly and a sliding block assembly structure are additionally arranged on the mold, so that green body forming and demolding can be assisted, and use is convenient.