A foldable frame, comprising: a base (401; 1801); a first fixing post; a second fixing post; a sliding frame (404; 1804; 2204; 2304); a table surface (405; 18051, 18052; 22051, 22052; 23051, 23052); wherein the first fixing post and the second fixing post are respectively fixed on both ends of the base; a first guide rail and a second guide rail are provided on the first fixing post (402; 1502) and the second fixing post respectively and opposite to each other, the sliding frame (404; 1804; 2204; 2304) is provided between the first guide rail and the second guide rail and adapted to slide up and down along the first guide rail and the second guide rail; the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is horizontally connected to a side of the sliding frame (404; 1804; 2204; 2304) and adapted to be rotated in a vertical plane around a joint between the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) and the sliding frame (404; 1104; 1804; 2204; 2304), the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is adapted to be horizontally positioned; an inclined lever (4071, 4072; 18071, 18072, 18073, 18074; 22071, 22072; 23071, 23072, 23073, 23074) is hinged to the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) at one end, and the other end of the inclined lever (4071, 4072; 18071, 18072, 18073, 18074; 22071, 22072; 23071, 23072, 23073, 23074) is hinged to the base; and wherein an active post (406; 18061, 18062; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) is further hinged to the back surface of the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052), wherein the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is horizontal when the bottom of the active post (406; 18061; 1806; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) and the bottom of the base (401; 701) are horizontal, characterised in that the active post (406; 18061, 18062; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) is further hinged to a transverse lever (408; 18081, 18082; 22081, 22082, 22083, 22084; 23081, 23082) at one end, and the other end of the transverse lever (408; 18081, 18082; 22081, 22082, 22083, 22084; 23081, 23082) is hinged to the sliding frame (404; 1804; 2204; 2304). a base (401; 1801); a first fixing post; a second fixing post; a sliding frame (404; 1804; 2204; 2304); a table surface (405; 18051, 18052; 22051, 22052; 23051, 23052); wherein the first fixing post and the second fixing post are respectively fixed on both ends of the base; a first guide rail and a second guide rail are provided on the first fixing post (402; 1502) and the second fixing post respectively and opposite to each other, the sliding frame (404; 1804; 2204; 2304) is provided between the first guide rail and the second guide rail and adapted to slide up and down along the first guide rail and the second guide rail; the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is horizontally connected to a side of the sliding frame (404; 1804; 2204; 2304) and adapted to be rotated in a vertical plane around a joint between the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) and the sliding frame (404; 1104; 1804; 2204; 2304), the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is adapted to be horizontally positioned; an inclined lever (4071, 4072; 18071, 18072, 18073, 18074; 22071, 22072; 23071, 23072, 23073, 23074) is hinged to the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) at one end, and the other end of the inclined lever (4071, 4072; 18071, 18072, 18073, 18074; 22071, 22072; 23071, 23072, 23073, 23074) is hinged to the base; and wherein an active post (406; 18061, 18062; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) is further hinged to the back surface of the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052), wherein the table surface (405; 18051, 18052; 22051, 22052; 23051, 23052) is horizontal when the bottom of the active post (406; 18061; 1806; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) and the bottom of the base (401; 701) are horizontal, characterised in that the active post (406; 18061, 18062; 22061, 22062, 22063, 22064; 23061, 23062, 23063, 23064) is further hinged to a transverse lever (408; 18081, 18082; 22081, 22082, 22083, 22084; 23081, 23082) at one end, and the other end of the transverse lever (408; 18081, 18082; 22081, 22082, 22083, 22084; 23081, 23082) is hinged to the sliding frame (404; 1804; 2204; 2304).