The invention discloses a platform adjustment mechanism of a photocuring 3D printer, and the photocuring 3D printer. The platform adjustment mechanism comprises a base plate, a forming platform plate,a vertical moving assembly, a connecting piece and a platform adjusting assembly; a resin groove is formed in the base plate; the plane, facing the resin groove, of the forming platform plate is a forming face; the vertical moving assembly is connected with the forming platform plate and controls the forming platform plate to move in the vertical direction; the connecting piece is connected withthe vertical moving assembly and the forming platform plate; the platform adjusting assembly is arranged between the connecting piece and the forming platform plate, used for adjusting the forming platform plate to be parallel to the bottom face of the resin groove, and comprises a positioning ball head, a positioning compression piece, a fastening piece and a connecting rod, the side face, facingthe forming platform plate, of the connecting piece is provided with a first groove part, and the positioning ball head and the positioning compression piece are both arranged in the first groove part; and the positioning compression piece sleeves the positioning ball head, the connecting rod is connected with the positioning ball head and the forming platform plate, a through hole is formed in the connecting piece, and the fastening piece penetrates through the through hole to compress the positioning compression piece so as to compress the positioning ball head.