The invention discloses a combined pouring and purifying system for automobile aluminium alloy wheels with big diameter being more than 26 inches; the system is composed of a control cabinet, compression and decompression pipes, side dies, a top die, a bottom die, one central pouring system and two lateral pouring system; the central pouring system is composed of a circular arc filter screen, an iron pouring gate, a ceramic vacuum cup and a ceramic liquid-rising pipe; each lateral pouring system is composed of a lateral pouring feeding inlet, a cap-shaped filter screen, another iron pouring gate, another ceramic vacuum cup, a ring-shaped sealing gasket and another ceramic liquid-rising pipe; the feeding interface of each lateral pouring system is assembled at the die assembly place of two side dies and a Lip middle-upper part area; the volume of each lateral pouring feeding inlet is 100-200cm<3>; the width of the section thereof is 2.0-4.0mm, and the height thereof is 25.0-50.0mm; the invention has the characteristics that the mould filling time is short; the casting period is short; the casting defect is less; the interior quality of a casting is excellent; the casting process is convenient to control, and the like.