A method for knitting a three-dimensional, in short 3D, shoe blank (100, 200, 200', 200") comprising: knitting at least a yarn to form an upper portion (112, 212), wherein when knitting the upper portion (112, 212), the knitting is gradually narrowed at two sides of the upper portion (112, 212), and a plurality of live stitches (11a~17a, 11b~17b) are preserved on the needle bed at the two sides of the upper portion (112, 212); continuing knitting and forming a front sole portion (120, 220) from the upper portion (112, 212), wherein when the knitting of the front sole portion (120, 220) reaches two sides of the front sole portion (120, 220), the live stitches (11a~17a, 11b~17b) preserved on the needle bed at the two sides of the upper portion (112, 212) are sequentially and respectively knitted with the two sides of the front sole portion (120, 220), so the upper portion (112, 212) is folded along a folding line (101, 201) and connected to the front sole portion (120, 220) to form a pocket structure with two connection lines (102, 103; 202, 203) formed at two opposite sides of the front sole portion (120, 220) and the upper portion (112, 212); continuing knitting and forming a rear portion from the front sole portion (120, 220), wherein when forming the rear portion, a plurality of live stitches (31a~38a, 31b~38b) are preserved on the needle bed at two sides of a rear end of the rear portion; and continuing knitting to form a heel portion with a predetermined number of stitches from a center of the rear end of the rear portion, wherein when the knitting of the heel portion reaches the predetermined number of stitches at two opposite sides of the heel portion, the live stitches preserved at the two sides of the rear end of the rear portion are sequentially and respectively knitted with the two opposite sides of the heel portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion with two joining lines (104a, 104b) formed between the heel portion and the rear portion at the two opposite sides of the heel portion, respectively, and the 3D shoe blank is formed as an integral knit fabric without any sewn portion among the upper portion (112, 212), the front sole portion (120, 220), the rear portion, and the heel portion, characterised by using a flat knitting machine and forming the integral knit fabric with the two connection lines (102, 103; 202, 203) extending outward and obliquely from two ends of the folding line (101, 201) at the side edges of the pocket structure toward an outer side of the rear portion, when the pocket structure is in a collapsed condition. knitting at least a yarn to form an upper portion (112, 212), wherein when knitting the upper portion (112, 212), the knitting is gradually narrowed at two sides of the upper portion (112, 212), and a plurality of live stitches (11a~17a, 11b~17b) are preserved on the needle bed at the two sides of the upper portion (112, 212); continuing knitting and forming a front sole portion (120, 220) from the upper portion (112, 212), wherein when the knitting of the front sole portion (120, 220) reaches two sides of the front sole portion (120, 220), the live stitches (11a~17a, 11b~17b) preserved on the needle bed at the two sides of the upper portion (112, 212) are sequentially and respectively knitted with the two sides of the front sole portion (120, 220), so the upper portion (112, 212) is folded along a folding line (101, 201) and connected to the front sole portion (120, 220) to form a pocket structure with two connection lines (102, 103; 202, 203) formed at two opposite sides of the front sole portion (120, 220) and the upper portion (112, 212); continuing knitting and forming a rear portion from the front sole portion (120, 220), wherein when forming the rear portion, a plurality of live stitches (31a~38a, 31b~38b) are preserved on the needle bed at two sides of a rear end of the rear portion; and continuing knitting to form a heel portion with a predetermined number of stitches from a center of the rear end of the rear portion, wherein when the knitting of the heel portion reaches the predetermined number of stitches at two opposite sides of the heel portion, the live stitches preserved at the two sides of the rear end of the rear portion are sequentially and respectively knitted with the two opposite sides of the heel portion, so the heel portion and the rear portion are combined to form a 3D rear shoe portion with two joining lines (104a, 104b) formed between the heel portion and the rear portion at the two opposite sides of the heel portion, respectively, and the 3D shoe blank is formed as an integral knit fabric without any sewn portion among the upper portion (112, 212), the front sole portion (120, 220), the rear portion, and the heel portion, characterised by using a flat knitting machine and forming the integral knit fabric with the two connection lines (102, 103; 202, 203) extending outward and obliquely from two ends of the folding line (101, 201) at the side edges of the pocket structure toward an outer side of the rear portion, when the pocket structure is in a collapsed condition.